[v19,0/4] Introduce usb charger framework to deal with the usb gadget power negotation

Commit Message

NeilBrown March 3, 2017, 2:23 a.m. UTC

On Mon, Feb 20 2017, Baolin Wang wrote:

> Currently the Linux kernel does not provide any standard integration of this
> feature that integrates the USB subsystem with the system power regulation
> provided by PMICs meaning that either vendors must add this in their kernels
> or USB gadget devices based on Linux (such as mobile phones) may not behave
> as they should. Thus provide a standard framework for doing this in kernel.
>
> Now introduce one user with wm831x_power to support and test the usb charger.
> Another user introduced to support charger detection by Jun Li:
> https://www.spinics.net/lists/linux-usb/msg139425.html
> Moreover there may be other potential users will use it in future. 
>
> 1. Before v19 patchset we've fixed below issues in extcon subsystem and usb
> phy driver, now all were merged. (Thanks for Neil's suggestion)
> (1) Have fixed the inconsistencies with USB connector types in extcon subsystem
> by following links:
> https://lkml.org/lkml/2016/12/21/13
> https://lkml.org/lkml/2016/12/21/15
> https://lkml.org/lkml/2016/12/21/79
> https://lkml.org/lkml/2017/1/3/13
>
> (2) Instead of using 'set_power' callback in phy drivers, we will introduce
> USB charger to set PMIC current drawn from USB configuration, moreover some
> 'set_power' callbacks did not implement anything to set PMIC current, thus
> remove them by following links:
> https://lkml.org/lkml/2017/1/18/436
> https://lkml.org/lkml/2017/1/18/439
> https://lkml.org/lkml/2017/1/18/438
> Now only two phy drivers (phy-isp1301-omap.c and phy-gpio-vbus-usb.c) still
> used 'set_power' callback to set current, we can remove them in future. (I
> have no platform with enabling these two phy drivers, so I can not test them
> if I converted 'set_power' callback to USB charger.)
>
> 2. Some issues pointed by Neil Brown were sill kept in this v19 patchset, and
> I expalined each issue and may be need discuss again:
> (1) Change all usb phys to register an extcon and to send appropriate notifications.
> Firstly, now only 3 USB phy drivers (phy-qcom-8x16-usb.c, phy-omap-otg.c and
> phy-msm-usb.c) had registered an extcon, mostly did not. I can not change all
> usb phys to register an extcon, since there are no extcon device to register
> for these different phy drivers.

You don't have to change every driver.  You just need to make it easy
and obvious how to change drivers in a consistent coherent way.
For a start you would add a 'struct extcon_dev' to 'struct usb_phy', and
possibly add or extend some 'static inline's in linux/usb/phy.h to send
notification on that extcon (if it is non-NULL).
e.g. usb_phy_vbus_on() could send an extcon notification.

Then any phy driver which adds support for setting phy->extcon_dev
appropriately, immediately gets the relevant notifications sent.


> Secondly, I also agreed with Peter's comments: Not only USB PHY to register
> an extcon, but also for the drivers which can detect USB charger type, it may
> be USB controller driver, USB type-c driver, pmic driver, and these drivers
> may not have an extcon device since the internal part can finish the vbus
> detect.

Whichever part can detect vbus, the driver for that part must be able to
find the extcon and trigger a notification.
Maybe one part can detect VBUS, another can measure the resistance on ID
and a third can work through the state machine to determine if D+ and D-
are shorted together.
Somehow these three need to work together to determine what is plugged
in to the external connection port.  Somewhere there much an 'extcon'
device which represents that port and which the three devices can find
and can interact with.
I think it makes sense for the usb_phy to be the connection point.  Each
of the devices can get to the phy, and the phy can get to the extcon.
It doesn't matter very much if the usb phy driver creates the extcon, or
if something else creates the extcon and the phy driver performs a
lookup to find it (e.g. based on devicetree info).

The point is that there is obviously an external physical connection,
and so there should be an 'extcon' device that represents it.


>
> (2) Change the notifier of usb_phy to be used consistently.
> Now only 3 phy drivers (phy-generic.c, phy-ab8500-usb.c and phy-gpio-vbus-usb.c)
> used the notifier of usb_phy. phy-generic.c and phy-gpio-vbus-usb.c were used to
> send out the connect events, and phy-ab8500-usb.c also was used to send out the
> MUSB connect events. There are no phy drivers will notify 'vbus_draw' information
> by the notifier of usb_phy, which was used consistently now.
> Moreover it is difficult to change the notifier of usb_phy to be used only to
> communicate the 'vbus_draw' information, since we need to refactor and test these
> related phy drivers, power drivers or some mfd drivers, which is a
> huge workload.

You missed drivers/usb/musb/omap2430.c in you list, but that hardly
matters.
phy-ab8500-usb.c appears to send vbus_draw information.

I understand your reluctance to change drivers that you cannot test.
An alternative it do change all the
  atomic_notifier_call_chain(.*notifier,
calls that don't pass a pointer to vbus_draw to pass NULL, and to
declare the passing of NULL to be deprecated (so hopefully people won't
use it in new code).
Then any notification callback that expects a current can just ignore
calls where the pointer is NULL.

The one difficulty with this is drivers/usb/gadget/udc/pxa27x_udc.c
It is the only driver which expects a 'gadget', and it doesn't really
need to as it already knows the gadget.
The patch below fixes this.
With that in place, phy-generic and phy-gpio-vbus-usb can be changed to
pass NULL.  When we can safely use the notifier to pass vbus_draw
information uniformly.

>
> (3) Still keep charger_type_show() API.
> Firstly I think we should combine all charger related information into one
> place for users, which is convenient.

convenience is very much a secondary issue.

> Secondly not only we get charger type from extcon, but also in some scenarios
> we can get charger type from USB controller driver, USB type-c driver, pmic
> driver, we should also need one place to export the charger type.

As I have said, all of these sources of information should feed into the
extcon.

There are ultimately two possible sources of information about the
current available from the usb port.
One is the physical properties of the cable, such as resistance of ID,
any short between D+ and D- etc.  Being properties of the cable, they
should be reported through the extcon.

The other is information gathered during the USB protocol handshake.
For USB2, this is the requested current of the profile that the host
activates.  This should be reported though the USB gadget device.

I don't know how USB3 and/or type-C work but I would be surprised if they
don't fit into the two cases above.  If you think otherwise, please
surprise me.  I'm always keen to learn.

If the extcon reports the type of cable detected, and the gadget reports
the result of any negotiation, then that is enough to determine the
charger type.  It doesn't need to be more convenient than that.


Thanks,
NeilBrown



From 75a77246d2e9224f579ab996640a435a1c587d5f Mon Sep 17 00:00:00 2001
From: NeilBrown <[e-mail]>
Date: Fri, 3 Mar 2017 13:05:17 +1100
Subject: [PATCH] usb: gadget: pxa27x: change event handler to not expect
 gadget.

We are planning to change the usb notifier to not pass a gadget,
as different drivers pass different things and consistency would
be nice.

The only driver to expect a gadget is pxa27x.
Unlike other drivers that register a usb notifier, pxa27x uses a static
notifier_block.  Other drivers embed a notifer_block in their data
struct so that struct can be access from the notifer callback.

So change pxa27x to use as embedded notifer_block, and to use that
to find the target gadget.
With this, it can ignore that pointer that is passed.  This will
allow us to change all calls that pass a gadget, to instead pass
NULL.

Signed-off-by: NeilBrown <[e-mail]>
---
 drivers/usb/gadget/udc/pxa27x_udc.c | 14 ++++++--------
 drivers/usb/gadget/udc/pxa27x_udc.h |  2 ++
 2 files changed, 8 insertions(+), 8 deletions(-)

Comments

(Exiting) Baolin Wang March 7, 2017, 9:38 a.m. UTC | #1

On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:
> On Mon, Feb 20 2017, Baolin Wang wrote:
>
>> Currently the Linux kernel does not provide any standard integration of this
>> feature that integrates the USB subsystem with the system power regulation
>> provided by PMICs meaning that either vendors must add this in their kernels
>> or USB gadget devices based on Linux (such as mobile phones) may not behave
>> as they should. Thus provide a standard framework for doing this in kernel.
>>
>> Now introduce one user with wm831x_power to support and test the usb charger.
>> Another user introduced to support charger detection by Jun Li:
>> https://www.spinics.net/lists/linux-usb/msg139425.html
>> Moreover there may be other potential users will use it in future.
>>
>> 1. Before v19 patchset we've fixed below issues in extcon subsystem and usb
>> phy driver, now all were merged. (Thanks for Neil's suggestion)
>> (1) Have fixed the inconsistencies with USB connector types in extcon subsystem
>> by following links:
>> https://lkml.org/lkml/2016/12/21/13
>> https://lkml.org/lkml/2016/12/21/15
>> https://lkml.org/lkml/2016/12/21/79
>> https://lkml.org/lkml/2017/1/3/13
>>
>> (2) Instead of using 'set_power' callback in phy drivers, we will introduce
>> USB charger to set PMIC current drawn from USB configuration, moreover some
>> 'set_power' callbacks did not implement anything to set PMIC current, thus
>> remove them by following links:
>> https://lkml.org/lkml/2017/1/18/436
>> https://lkml.org/lkml/2017/1/18/439
>> https://lkml.org/lkml/2017/1/18/438
>> Now only two phy drivers (phy-isp1301-omap.c and phy-gpio-vbus-usb.c) still
>> used 'set_power' callback to set current, we can remove them in future. (I
>> have no platform with enabling these two phy drivers, so I can not test them
>> if I converted 'set_power' callback to USB charger.)
>>
>> 2. Some issues pointed by Neil Brown were sill kept in this v19 patchset, and
>> I expalined each issue and may be need discuss again:
>> (1) Change all usb phys to register an extcon and to send appropriate notifications.
>> Firstly, now only 3 USB phy drivers (phy-qcom-8x16-usb.c, phy-omap-otg.c and
>> phy-msm-usb.c) had registered an extcon, mostly did not. I can not change all
>> usb phys to register an extcon, since there are no extcon device to register
>> for these different phy drivers.
>
> You don't have to change every driver.  You just need to make it easy
> and obvious how to change drivers in a consistent coherent way.
> For a start you would add a 'struct extcon_dev' to 'struct usb_phy', and
> possibly add or extend some 'static inline's in linux/usb/phy.h to send
> notification on that extcon (if it is non-NULL).
> e.g. usb_phy_vbus_on() could send an extcon notification.
>
> Then any phy driver which adds support for setting phy->extcon_dev
> appropriately, immediately gets the relevant notifications sent.

OK. We can make these extcon related code into phy common part.

>
>> Secondly, I also agreed with Peter's comments: Not only USB PHY to register
>> an extcon, but also for the drivers which can detect USB charger type, it may
>> be USB controller driver, USB type-c driver, pmic driver, and these drivers
>> may not have an extcon device since the internal part can finish the vbus
>> detect.
>
> Whichever part can detect vbus, the driver for that part must be able to
> find the extcon and trigger a notification.
> Maybe one part can detect VBUS, another can measure the resistance on ID
> and a third can work through the state machine to determine if D+ and D-
> are shorted together.
> Somehow these three need to work together to determine what is plugged
> in to the external connection port.  Somewhere there much an 'extcon'
> device which represents that port and which the three devices can find
> and can interact with.
> I think it makes sense for the usb_phy to be the connection point.  Each
> of the devices can get to the phy, and the phy can get to the extcon.
> It doesn't matter very much if the usb phy driver creates the extcon, or
> if something else creates the extcon and the phy driver performs a
> lookup to find it (e.g. based on devicetree info).
>
> The point is that there is obviously an external physical connection,
> and so there should be an 'extcon' device that represents it.

Peter & Jun, is it OK for you every phy has one extcon device to
receive VBUS notification, especially for detecting the charger type
by software?

>
>>
>> (2) Change the notifier of usb_phy to be used consistently.
>> Now only 3 phy drivers (phy-generic.c, phy-ab8500-usb.c and phy-gpio-vbus-usb.c)
>> used the notifier of usb_phy. phy-generic.c and phy-gpio-vbus-usb.c were used to
>> send out the connect events, and phy-ab8500-usb.c also was used to send out the
>> MUSB connect events. There are no phy drivers will notify 'vbus_draw' information
>> by the notifier of usb_phy, which was used consistently now.
>> Moreover it is difficult to change the notifier of usb_phy to be used only to
>> communicate the 'vbus_draw' information, since we need to refactor and test these
>> related phy drivers, power drivers or some mfd drivers, which is a
>> huge workload.
>
> You missed drivers/usb/musb/omap2430.c in you list, but that hardly
> matters.

But it did not use the notifier of usb_phy.

> phy-ab8500-usb.c appears to send vbus_draw information.

Users will not use the vbus_draw information send from phy-ab8500-usb.c

>
> I understand your reluctance to change drivers that you cannot test.
> An alternative it do change all the
>   atomic_notifier_call_chain(.*notifier,
> calls that don't pass a pointer to vbus_draw to pass NULL, and to
> declare the passing of NULL to be deprecated (so hopefully people won't
> use it in new code).
> Then any notification callback that expects a current can just ignore
> calls where the pointer is NULL.

I am afraid if it is enough to send out vbus draw information from USB
phy driver, for example you will miss super speed (900mA), which need
get the speed information from gadget driver.

>
> The one difficulty with this is drivers/usb/gadget/udc/pxa27x_udc.c
> It is the only driver which expects a 'gadget', and it doesn't really
> need to as it already knows the gadget.
> The patch below fixes this.
> With that in place, phy-generic and phy-gpio-vbus-usb can be changed to
> pass NULL.  When we can safely use the notifier to pass vbus_draw
> information uniformly.
>
>>
>> (3) Still keep charger_type_show() API.
>> Firstly I think we should combine all charger related information into one
>> place for users, which is convenient.
>
> convenience is very much a secondary issue.
>
>> Secondly not only we get charger type from extcon, but also in some scenarios
>> we can get charger type from USB controller driver, USB type-c driver, pmic
>> driver, we should also need one place to export the charger type.
>
> As I have said, all of these sources of information should feed into the
> extcon.
>
> There are ultimately two possible sources of information about the
> current available from the usb port.
> One is the physical properties of the cable, such as resistance of ID,
> any short between D+ and D- etc.  Being properties of the cable, they
> should be reported through the extcon.
>
> The other is information gathered during the USB protocol handshake.
> For USB2, this is the requested current of the profile that the host
> activates.  This should be reported though the USB gadget device.
>
> I don't know how USB3 and/or type-C work but I would be surprised if they
> don't fit into the two cases above.  If you think otherwise, please
> surprise me.  I'm always keen to learn.
>
> If the extcon reports the type of cable detected, and the gadget reports
> the result of any negotiation, then that is enough to determine the
> charger type.  It doesn't need to be more convenient than that.

If we are all agree we did not need the USB charger, then we can add
'current' attribute of USB gadget device.
Thanks for your suggestion.

Jun Li March 9, 2017, 1:50 a.m. UTC | #2

Hi,

> -----Original Message-----

> From: Baolin Wang [mailto:[e-mail]]

> Sent: Tuesday, March 07, 2017 5:39 PM

> To: NeilBrown <[e-mail]>

> Cc: Felipe Balbi <[e-mail]>; Greg KH <[e-mail]>;

> Sebastian Reichel <[e-mail]>; Dmitry Eremin-Solenikov

> <[e-mail]>; David Woodhouse <[e-mail]>;

> [e-mail]; Jun Li <[e-mail]>; Marek Szyprowski

> <[e-mail]>; Ruslan Bilovol <[e-mail]>;

> Peter Chen <[e-mail]>; Alan Stern

> <[e-mail]>; [e-mail]; Yoshihiro Shimoda

> <[e-mail]>; Lee Jones <[e-mail]>;

> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;

> Charles Keepax <[e-mail]>;

> [e-mail]; Linux PM list <linux-

> [e-mail]>; USB <[e-mail]>; device-

> [e-mail]; LKML <[e-mail]>

> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with

> the usb gadget power negotation

> 

> On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:

> > On Mon, Feb 20 2017, Baolin Wang wrote:

> >

> >> Currently the Linux kernel does not provide any standard integration

> >> of this feature that integrates the USB subsystem with the system

> >> power regulation provided by PMICs meaning that either vendors must

> >> add this in their kernels or USB gadget devices based on Linux (such

> >> as mobile phones) may not behave as they should. Thus provide a

> standard framework for doing this in kernel.

> >>

> >> Now introduce one user with wm831x_power to support and test the usb

> charger.

> >> Another user introduced to support charger detection by Jun Li:

> >> https://www.spinics.net/lists/linux-usb/msg139425.html

> >> Moreover there may be other potential users will use it in future.

> >>

> >> 1. Before v19 patchset we've fixed below issues in extcon subsystem

> >> and usb phy driver, now all were merged. (Thanks for Neil's

> >> suggestion)

> >> (1) Have fixed the inconsistencies with USB connector types in extcon

> >> subsystem by following links:

> >> https://lkml.org/lkml/2016/12/21/13

> >> https://lkml.org/lkml/2016/12/21/15

> >> https://lkml.org/lkml/2016/12/21/79

> >> https://lkml.org/lkml/2017/1/3/13

> >>

> >> (2) Instead of using 'set_power' callback in phy drivers, we will

> >> introduce USB charger to set PMIC current drawn from USB

> >> configuration, moreover some 'set_power' callbacks did not implement

> >> anything to set PMIC current, thus remove them by following links:

> >> https://lkml.org/lkml/2017/1/18/436

> >> https://lkml.org/lkml/2017/1/18/439

> >> https://lkml.org/lkml/2017/1/18/438

> >> Now only two phy drivers (phy-isp1301-omap.c and phy-gpio-vbus-usb.c)

> >> still used 'set_power' callback to set current, we can remove them in

> >> future. (I have no platform with enabling these two phy drivers, so I

> >> can not test them if I converted 'set_power' callback to USB

> >> charger.)

> >>

> >> 2. Some issues pointed by Neil Brown were sill kept in this v19

> >> patchset, and I expalined each issue and may be need discuss again:

> >> (1) Change all usb phys to register an extcon and to send appropriate

> notifications.

> >> Firstly, now only 3 USB phy drivers (phy-qcom-8x16-usb.c,

> >> phy-omap-otg.c and

> >> phy-msm-usb.c) had registered an extcon, mostly did not. I can not

> >> change all usb phys to register an extcon, since there are no extcon

> >> device to register for these different phy drivers.

> >

> > You don't have to change every driver.  You just need to make it easy

> > and obvious how to change drivers in a consistent coherent way.

> > For a start you would add a 'struct extcon_dev' to 'struct usb_phy',

> > and possibly add or extend some 'static inline's in linux/usb/phy.h to

> > send notification on that extcon (if it is non-NULL).

> > e.g. usb_phy_vbus_on() could send an extcon notification.

> >

> > Then any phy driver which adds support for setting phy->extcon_dev

> > appropriately, immediately gets the relevant notifications sent.

> 

> OK. We can make these extcon related code into phy common part.

> 	


Will generic phy need add extcon as well?

> >

> >> Secondly, I also agreed with Peter's comments: Not only USB PHY to

> >> register an extcon, but also for the drivers which can detect USB

> >> charger type, it may be USB controller driver, USB type-c driver,

> >> pmic driver, and these drivers may not have an extcon device since

> >> the internal part can finish the vbus detect.

> >

> > Whichever part can detect vbus, the driver for that part must be able

> > to find the extcon and trigger a notification.

> > Maybe one part can detect VBUS, another can measure the resistance on

> > ID and a third can work through the state machine to determine if D+

> > and D- are shorted together.

> > Somehow these three need to work together to determine what is

> plugged

> > in to the external connection port.  Somewhere there much an 'extcon'

> > device which represents that port and which the three devices can find

> > and can interact with.

> > I think it makes sense for the usb_phy to be the connection point.

> > Each of the devices can get to the phy, and the phy can get to the extcon.

> > It doesn't matter very much if the usb phy driver creates the extcon,

> > or if something else creates the extcon and the phy driver performs a

> > lookup to find it (e.g. based on devicetree info).

> >

> > The point is that there is obviously an external physical connection,

> > and so there should be an 'extcon' device that represents it.

> 

> Peter & Jun, is it OK for you every phy has one extcon device to receive VBUS

> notification, especially for detecting the charger type by software?

> 


My understanding is phy/usb_phy as the connection point, will send the notification
to PMIC driver which actually control the charge current, also this will be done in
your common framework, right?

Li Jun 

> >

> >>

> >> (2) Change the notifier of usb_phy to be used consistently.

> >> Now only 3 phy drivers (phy-generic.c, phy-ab8500-usb.c and

> >> phy-gpio-vbus-usb.c) used the notifier of usb_phy. phy-generic.c and

> >> phy-gpio-vbus-usb.c were used to send out the connect events, and

> >> phy-ab8500-usb.c also was used to send out the MUSB connect events.

> >> There are no phy drivers will notify 'vbus_draw' information by the

> notifier of usb_phy, which was used consistently now.

> >> Moreover it is difficult to change the notifier of usb_phy to be used

> >> only to communicate the 'vbus_draw' information, since we need to

> >> refactor and test these related phy drivers, power drivers or some

> >> mfd drivers, which is a huge workload.

> >

> > You missed drivers/usb/musb/omap2430.c in you list, but that hardly

> > matters.

> 

> But it did not use the notifier of usb_phy.

> 

> > phy-ab8500-usb.c appears to send vbus_draw information.

> 

> Users will not use the vbus_draw information send from phy-ab8500-usb.c

> 

> >

> > I understand your reluctance to change drivers that you cannot test.

> > An alternative it do change all the

> >   atomic_notifier_call_chain(.*notifier,

> > calls that don't pass a pointer to vbus_draw to pass NULL, and to

> > declare the passing of NULL to be deprecated (so hopefully people

> > won't use it in new code).

> > Then any notification callback that expects a current can just ignore

> > calls where the pointer is NULL.

> 

> I am afraid if it is enough to send out vbus draw information from USB phy

> driver, for example you will miss super speed (900mA), which need get the

> speed information from gadget driver.

> 

> >

> > The one difficulty with this is drivers/usb/gadget/udc/pxa27x_udc.c

> > It is the only driver which expects a 'gadget', and it doesn't really

> > need to as it already knows the gadget.

> > The patch below fixes this.

> > With that in place, phy-generic and phy-gpio-vbus-usb can be changed

> > to pass NULL.  When we can safely use the notifier to pass vbus_draw

> > information uniformly.

> >

> >>

> >> (3) Still keep charger_type_show() API.

> >> Firstly I think we should combine all charger related information

> >> into one place for users, which is convenient.

> >

> > convenience is very much a secondary issue.

> >

> >> Secondly not only we get charger type from extcon, but also in some

> >> scenarios we can get charger type from USB controller driver, USB

> >> type-c driver, pmic driver, we should also need one place to export the

> charger type.

> >

> > As I have said, all of these sources of information should feed into

> > the extcon.

> >

> > There are ultimately two possible sources of information about the

> > current available from the usb port.

> > One is the physical properties of the cable, such as resistance of ID,

> > any short between D+ and D- etc.  Being properties of the cable, they

> > should be reported through the extcon.

> >

> > The other is information gathered during the USB protocol handshake.

> > For USB2, this is the requested current of the profile that the host

> > activates.  This should be reported though the USB gadget device.

> >

> > I don't know how USB3 and/or type-C work but I would be surprised if

> > they don't fit into the two cases above.  If you think otherwise,

> > please surprise me.  I'm always keen to learn.

> >

> > If the extcon reports the type of cable detected, and the gadget

> > reports the result of any negotiation, then that is enough to

> > determine the charger type.  It doesn't need to be more convenient than

> that.

> 

> If we are all agree we did not need the USB charger, then we can add

> 'current' attribute of USB gadget device.

> Thanks for your suggestion.

> 

> --

> Baolin.wang

> Best Regards

(Exiting) Baolin Wang March 9, 2017, 6:10 a.m. UTC | #3

Hi,

On 9 March 2017 at 09:50, Jun Li <[e-mail]> wrote:
> Hi,
>
>> -----Original Message-----
>> From: Baolin Wang [mailto:[e-mail]]
>> Sent: Tuesday, March 07, 2017 5:39 PM
>> To: NeilBrown <[e-mail]>
>> Cc: Felipe Balbi <[e-mail]>; Greg KH <[e-mail]>;
>> Sebastian Reichel <[e-mail]>; Dmitry Eremin-Solenikov
>> <[e-mail]>; David Woodhouse <[e-mail]>;
>> [e-mail]; Jun Li <[e-mail]>; Marek Szyprowski
>> <[e-mail]>; Ruslan Bilovol <[e-mail]>;
>> Peter Chen <[e-mail]>; Alan Stern
>> <[e-mail]>; [e-mail]; Yoshihiro Shimoda
>> <[e-mail]>; Lee Jones <[e-mail]>;
>> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;
>> Charles Keepax <[e-mail]>;
>> [e-mail]; Linux PM list <linux-
>> [e-mail]>; USB <[e-mail]>; device-
>> [e-mail]; LKML <[e-mail]>
>> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with
>> the usb gadget power negotation
>>
>> On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:
>> > On Mon, Feb 20 2017, Baolin Wang wrote:
>> >
>> >> Currently the Linux kernel does not provide any standard integration
>> >> of this feature that integrates the USB subsystem with the system
>> >> power regulation provided by PMICs meaning that either vendors must
>> >> add this in their kernels or USB gadget devices based on Linux (such
>> >> as mobile phones) may not behave as they should. Thus provide a
>> standard framework for doing this in kernel.
>> >>
>> >> Now introduce one user with wm831x_power to support and test the usb
>> charger.
>> >> Another user introduced to support charger detection by Jun Li:
>> >> https://www.spinics.net/lists/linux-usb/msg139425.html
>> >> Moreover there may be other potential users will use it in future.
>> >>
>> >> 1. Before v19 patchset we've fixed below issues in extcon subsystem
>> >> and usb phy driver, now all were merged. (Thanks for Neil's
>> >> suggestion)
>> >> (1) Have fixed the inconsistencies with USB connector types in extcon
>> >> subsystem by following links:
>> >> https://lkml.org/lkml/2016/12/21/13
>> >> https://lkml.org/lkml/2016/12/21/15
>> >> https://lkml.org/lkml/2016/12/21/79
>> >> https://lkml.org/lkml/2017/1/3/13
>> >>
>> >> (2) Instead of using 'set_power' callback in phy drivers, we will
>> >> introduce USB charger to set PMIC current drawn from USB
>> >> configuration, moreover some 'set_power' callbacks did not implement
>> >> anything to set PMIC current, thus remove them by following links:
>> >> https://lkml.org/lkml/2017/1/18/436
>> >> https://lkml.org/lkml/2017/1/18/439
>> >> https://lkml.org/lkml/2017/1/18/438
>> >> Now only two phy drivers (phy-isp1301-omap.c and phy-gpio-vbus-usb.c)
>> >> still used 'set_power' callback to set current, we can remove them in
>> >> future. (I have no platform with enabling these two phy drivers, so I
>> >> can not test them if I converted 'set_power' callback to USB
>> >> charger.)
>> >>
>> >> 2. Some issues pointed by Neil Brown were sill kept in this v19
>> >> patchset, and I expalined each issue and may be need discuss again:
>> >> (1) Change all usb phys to register an extcon and to send appropriate
>> notifications.
>> >> Firstly, now only 3 USB phy drivers (phy-qcom-8x16-usb.c,
>> >> phy-omap-otg.c and
>> >> phy-msm-usb.c) had registered an extcon, mostly did not. I can not
>> >> change all usb phys to register an extcon, since there are no extcon
>> >> device to register for these different phy drivers.
>> >
>> > You don't have to change every driver.  You just need to make it easy
>> > and obvious how to change drivers in a consistent coherent way.
>> > For a start you would add a 'struct extcon_dev' to 'struct usb_phy',
>> > and possibly add or extend some 'static inline's in linux/usb/phy.h to
>> > send notification on that extcon (if it is non-NULL).
>> > e.g. usb_phy_vbus_on() could send an extcon notification.
>> >
>> > Then any phy driver which adds support for setting phy->extcon_dev
>> > appropriately, immediately gets the relevant notifications sent.
>>
>> OK. We can make these extcon related code into phy common part.
>>
>
> Will generic phy need add extcon as well?

Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which will
be common code.

>
>> >
>> >> Secondly, I also agreed with Peter's comments: Not only USB PHY to
>> >> register an extcon, but also for the drivers which can detect USB
>> >> charger type, it may be USB controller driver, USB type-c driver,
>> >> pmic driver, and these drivers may not have an extcon device since
>> >> the internal part can finish the vbus detect.
>> >
>> > Whichever part can detect vbus, the driver for that part must be able
>> > to find the extcon and trigger a notification.
>> > Maybe one part can detect VBUS, another can measure the resistance on
>> > ID and a third can work through the state machine to determine if D+
>> > and D- are shorted together.
>> > Somehow these three need to work together to determine what is
>> plugged
>> > in to the external connection port.  Somewhere there much an 'extcon'
>> > device which represents that port and which the three devices can find
>> > and can interact with.
>> > I think it makes sense for the usb_phy to be the connection point.
>> > Each of the devices can get to the phy, and the phy can get to the extcon.
>> > It doesn't matter very much if the usb phy driver creates the extcon,
>> > or if something else creates the extcon and the phy driver performs a
>> > lookup to find it (e.g. based on devicetree info).
>> >
>> > The point is that there is obviously an external physical connection,
>> > and so there should be an 'extcon' device that represents it.
>>
>> Peter & Jun, is it OK for you every phy has one extcon device to receive VBUS
>> notification, especially for detecting the charger type by software?
>>
>
> My understanding is phy/usb_phy as the connection point, will send the notification
> to PMIC driver which actually control the charge current, also this will be done in
> your common framework, right?

Not in USB charger framework. If we are all agree every usb_phy can
register one extcon device, can get correct charger type and send out
correct vbus_draw information, then we don't need USB charger
framework as Neil suggested. So this will be okay for your case
(especially for detecting the charger type by software) ?

>> >
>> >>
>> >> (2) Change the notifier of usb_phy to be used consistently.
>> >> Now only 3 phy drivers (phy-generic.c, phy-ab8500-usb.c and
>> >> phy-gpio-vbus-usb.c) used the notifier of usb_phy. phy-generic.c and
>> >> phy-gpio-vbus-usb.c were used to send out the connect events, and
>> >> phy-ab8500-usb.c also was used to send out the MUSB connect events.
>> >> There are no phy drivers will notify 'vbus_draw' information by the
>> notifier of usb_phy, which was used consistently now.
>> >> Moreover it is difficult to change the notifier of usb_phy to be used
>> >> only to communicate the 'vbus_draw' information, since we need to
>> >> refactor and test these related phy drivers, power drivers or some
>> >> mfd drivers, which is a huge workload.
>> >
>> > You missed drivers/usb/musb/omap2430.c in you list, but that hardly
>> > matters.
>>
>> But it did not use the notifier of usb_phy.
>>
>> > phy-ab8500-usb.c appears to send vbus_draw information.
>>
>> Users will not use the vbus_draw information send from phy-ab8500-usb.c
>>
>> >
>> > I understand your reluctance to change drivers that you cannot test.
>> > An alternative it do change all the
>> >   atomic_notifier_call_chain(.*notifier,
>> > calls that don't pass a pointer to vbus_draw to pass NULL, and to
>> > declare the passing of NULL to be deprecated (so hopefully people
>> > won't use it in new code).
>> > Then any notification callback that expects a current can just ignore
>> > calls where the pointer is NULL.
>>
>> I am afraid if it is enough to send out vbus draw information from USB phy
>> driver, for example you will miss super speed (900mA), which need get the
>> speed information from gadget driver.
>>
>> >
>> > The one difficulty with this is drivers/usb/gadget/udc/pxa27x_udc.c
>> > It is the only driver which expects a 'gadget', and it doesn't really
>> > need to as it already knows the gadget.
>> > The patch below fixes this.
>> > With that in place, phy-generic and phy-gpio-vbus-usb can be changed
>> > to pass NULL.  When we can safely use the notifier to pass vbus_draw
>> > information uniformly.
>> >
>> >>
>> >> (3) Still keep charger_type_show() API.
>> >> Firstly I think we should combine all charger related information
>> >> into one place for users, which is convenient.
>> >
>> > convenience is very much a secondary issue.
>> >
>> >> Secondly not only we get charger type from extcon, but also in some
>> >> scenarios we can get charger type from USB controller driver, USB
>> >> type-c driver, pmic driver, we should also need one place to export the
>> charger type.
>> >
>> > As I have said, all of these sources of information should feed into
>> > the extcon.
>> >
>> > There are ultimately two possible sources of information about the
>> > current available from the usb port.
>> > One is the physical properties of the cable, such as resistance of ID,
>> > any short between D+ and D- etc.  Being properties of the cable, they
>> > should be reported through the extcon.
>> >
>> > The other is information gathered during the USB protocol handshake.
>> > For USB2, this is the requested current of the profile that the host
>> > activates.  This should be reported though the USB gadget device.
>> >
>> > I don't know how USB3 and/or type-C work but I would be surprised if
>> > they don't fit into the two cases above.  If you think otherwise,
>> > please surprise me.  I'm always keen to learn.
>> >
>> > If the extcon reports the type of cable detected, and the gadget
>> > reports the result of any negotiation, then that is enough to
>> > determine the charger type.  It doesn't need to be more convenient than
>> that.
>>
>> If we are all agree we did not need the USB charger, then we can add
>> 'current' attribute of USB gadget device.
>> Thanks for your suggestion.
>>
>> --
>> Baolin.wang
>> Best Regards

Jun Li March 9, 2017, 10:34 a.m. UTC | #4

> -----Original Message-----

> From: Baolin Wang [mailto:[e-mail]]

> Sent: Thursday, March 09, 2017 2:11 PM

> To: Jun Li <[e-mail]>

> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH

> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry

> Eremin-Solenikov <[e-mail]>; David Woodhouse

> <[e-mail]>; [e-mail]; Marek Szyprowski

> <[e-mail]>; Ruslan Bilovol <[e-mail]>;

> Peter Chen <[e-mail]>; Alan Stern

> <[e-mail]>; [e-mail]; Yoshihiro Shimoda

> <[e-mail]>; Lee Jones <[e-mail]>;

> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;

> Charles Keepax <[e-mail]>;

> [e-mail]; Linux PM list <linux-

> [e-mail]>; USB <[e-mail]>; device-

> [e-mail]; LKML <[e-mail]>

> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with

> the usb gadget power negotation

> 

> Hi,

> 

> On 9 March 2017 at 09:50, Jun Li <[e-mail]> wrote:

> > Hi,

> >

> >> -----Original Message-----

> >> From: Baolin Wang [mailto:[e-mail]]

> >> Sent: Tuesday, March 07, 2017 5:39 PM

> >> To: NeilBrown <[e-mail]>

> >> Cc: Felipe Balbi <[e-mail]>; Greg KH

> >> <[e-mail]>; Sebastian Reichel <[e-mail]>;

> >> Dmitry Eremin-Solenikov <[e-mail]>; David Woodhouse

> >> <[e-mail]>; [e-mail]; Jun Li <[e-mail]>;

> >> Marek Szyprowski <[e-mail]>; Ruslan Bilovol

> >> <[e-mail]>; Peter Chen <[e-mail]>;

> >> Alan Stern <[e-mail]>; [e-mail];

> >> Yoshihiro Shimoda <[e-mail]>; Lee Jones

> >> <[e-mail]>; Mark Brown <[e-mail]>; John Stultz

> >> <[e-mail]>; Charles Keepax

> >> <[e-mail]>;

> >> [e-mail]; Linux PM list <linux-

> >> [e-mail]>; USB <[e-mail]>; device-

> >> [e-mail]; LKML

> >> <[e-mail]>

> >> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal

> >> with the usb gadget power negotation

> >>

> >> On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:

> >> > On Mon, Feb 20 2017, Baolin Wang wrote:

> >> >

> >> >> Currently the Linux kernel does not provide any standard

> >> >> integration of this feature that integrates the USB subsystem with

> >> >> the system power regulation provided by PMICs meaning that either

> >> >> vendors must add this in their kernels or USB gadget devices based

> >> >> on Linux (such as mobile phones) may not behave as they should.

> >> >> Thus provide a

> >> standard framework for doing this in kernel.

> >> >>

> >> >> Now introduce one user with wm831x_power to support and test the

> >> >> usb

> >> charger.

> >> >> Another user introduced to support charger detection by Jun Li:

> >> >> https://www.spinics.net/lists/linux-usb/msg139425.html

> >> >> Moreover there may be other potential users will use it in future.

> >> >>

> >> >> 1. Before v19 patchset we've fixed below issues in extcon

> >> >> subsystem and usb phy driver, now all were merged. (Thanks for

> >> >> Neil's

> >> >> suggestion)

> >> >> (1) Have fixed the inconsistencies with USB connector types in

> >> >> extcon subsystem by following links:

> >> >> https://lkml.org/lkml/2016/12/21/13

> >> >> https://lkml.org/lkml/2016/12/21/15

> >> >> https://lkml.org/lkml/2016/12/21/79

> >> >> https://lkml.org/lkml/2017/1/3/13

> >> >>

> >> >> (2) Instead of using 'set_power' callback in phy drivers, we will

> >> >> introduce USB charger to set PMIC current drawn from USB

> >> >> configuration, moreover some 'set_power' callbacks did not

> >> >> implement anything to set PMIC current, thus remove them by

> following links:

> >> >> https://lkml.org/lkml/2017/1/18/436

> >> >> https://lkml.org/lkml/2017/1/18/439

> >> >> https://lkml.org/lkml/2017/1/18/438

> >> >> Now only two phy drivers (phy-isp1301-omap.c and

> >> >> phy-gpio-vbus-usb.c) still used 'set_power' callback to set

> >> >> current, we can remove them in future. (I have no platform with

> >> >> enabling these two phy drivers, so I can not test them if I

> >> >> converted 'set_power' callback to USB

> >> >> charger.)

> >> >>

> >> >> 2. Some issues pointed by Neil Brown were sill kept in this v19

> >> >> patchset, and I expalined each issue and may be need discuss again:

> >> >> (1) Change all usb phys to register an extcon and to send

> >> >> appropriate

> >> notifications.

> >> >> Firstly, now only 3 USB phy drivers (phy-qcom-8x16-usb.c,

> >> >> phy-omap-otg.c and

> >> >> phy-msm-usb.c) had registered an extcon, mostly did not. I can not

> >> >> change all usb phys to register an extcon, since there are no

> >> >> extcon device to register for these different phy drivers.

> >> >

> >> > You don't have to change every driver.  You just need to make it

> >> > easy and obvious how to change drivers in a consistent coherent way.

> >> > For a start you would add a 'struct extcon_dev' to 'struct

> >> > usb_phy', and possibly add or extend some 'static inline's in

> >> > linux/usb/phy.h to send notification on that extcon (if it is non-NULL).

> >> > e.g. usb_phy_vbus_on() could send an extcon notification.

> >> >

> >> > Then any phy driver which adds support for setting phy->extcon_dev

> >> > appropriately, immediately gets the relevant notifications sent.

> >>

> >> OK. We can make these extcon related code into phy common part.

> >>

> >

> > Will generic phy need add extcon as well?

> 

> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which will be common

> code.

> 


I mean the common code need add 'struct extcon_dev' into both 'struct phy' and
'struct usb_phy', right? as some/new usb phy use that generic phy driver.

> >

> >> >

> >> >> Secondly, I also agreed with Peter's comments: Not only USB PHY to

> >> >> register an extcon, but also for the drivers which can detect USB

> >> >> charger type, it may be USB controller driver, USB type-c driver,

> >> >> pmic driver, and these drivers may not have an extcon device since

> >> >> the internal part can finish the vbus detect.

> >> >

> >> > Whichever part can detect vbus, the driver for that part must be

> >> > able to find the extcon and trigger a notification.

> >> > Maybe one part can detect VBUS, another can measure the resistance

> >> > on ID and a third can work through the state machine to determine

> >> > if D+ and D- are shorted together.

> >> > Somehow these three need to work together to determine what is

> >> plugged

> >> > in to the external connection port.  Somewhere there much an 'extcon'

> >> > device which represents that port and which the three devices can

> >> > find and can interact with.

> >> > I think it makes sense for the usb_phy to be the connection point.

> >> > Each of the devices can get to the phy, and the phy can get to the

> extcon.

> >> > It doesn't matter very much if the usb phy driver creates the

> >> > extcon, or if something else creates the extcon and the phy driver

> >> > performs a lookup to find it (e.g. based on devicetree info).

> >> >

> >> > The point is that there is obviously an external physical

> >> > connection, and so there should be an 'extcon' device that represents it.

> >>

> >> Peter & Jun, is it OK for you every phy has one extcon device to

> >> receive VBUS notification, especially for detecting the charger type by

> software?

> >>

> >

> > My understanding is phy/usb_phy as the connection point, will send the

> > notification to PMIC driver which actually control the charge current,

> > also this will be done in your common framework, right?

> 

> Not in USB charger framework. If we are all agree every usb_phy can register

> one extcon device, can get correct charger type and send out correct

> vbus_draw information, then we don't need USB charger framework as Neil

> suggested. So this will be okay for your case (especially for detecting the

> charger type by software) ?


In my case, charger detection is done by controller driver and I need do charger
type detection internally, and only pass the current draw info via phy which will
send out, this seems ok for me, but I think it will be good if you or someone can
show us an example user based on the design Neil suggested.
Will you work out that common code if this USB charger framework is not needed?

Li Jun
> 

> >> >

> >> >>

> >> >> (2) Change the notifier of usb_phy to be used consistently.

> >> >> Now only 3 phy drivers (phy-generic.c, phy-ab8500-usb.c and

> >> >> phy-gpio-vbus-usb.c) used the notifier of usb_phy. phy-generic.c

> >> >> and phy-gpio-vbus-usb.c were used to send out the connect events,

> >> >> and phy-ab8500-usb.c also was used to send out the MUSB connect

> events.

> >> >> There are no phy drivers will notify 'vbus_draw' information by

> >> >> the

> >> notifier of usb_phy, which was used consistently now.

> >> >> Moreover it is difficult to change the notifier of usb_phy to be

> >> >> used only to communicate the 'vbus_draw' information, since we

> >> >> need to refactor and test these related phy drivers, power drivers

> >> >> or some mfd drivers, which is a huge workload.

> >> >

> >> > You missed drivers/usb/musb/omap2430.c in you list, but that hardly

> >> > matters.

> >>

> >> But it did not use the notifier of usb_phy.

> >>

> >> > phy-ab8500-usb.c appears to send vbus_draw information.

> >>

> >> Users will not use the vbus_draw information send from

> >> phy-ab8500-usb.c

> >>

> >> >

> >> > I understand your reluctance to change drivers that you cannot test.

> >> > An alternative it do change all the

> >> >   atomic_notifier_call_chain(.*notifier,

> >> > calls that don't pass a pointer to vbus_draw to pass NULL, and to

> >> > declare the passing of NULL to be deprecated (so hopefully people

> >> > won't use it in new code).

> >> > Then any notification callback that expects a current can just

> >> > ignore calls where the pointer is NULL.

> >>

> >> I am afraid if it is enough to send out vbus draw information from

> >> USB phy driver, for example you will miss super speed (900mA), which

> >> need get the speed information from gadget driver.

> >>

> >> >

> >> > The one difficulty with this is drivers/usb/gadget/udc/pxa27x_udc.c

> >> > It is the only driver which expects a 'gadget', and it doesn't

> >> > really need to as it already knows the gadget.

> >> > The patch below fixes this.

> >> > With that in place, phy-generic and phy-gpio-vbus-usb can be

> >> > changed to pass NULL.  When we can safely use the notifier to pass

> >> > vbus_draw information uniformly.

> >> >

> >> >>

> >> >> (3) Still keep charger_type_show() API.

> >> >> Firstly I think we should combine all charger related information

> >> >> into one place for users, which is convenient.

> >> >

> >> > convenience is very much a secondary issue.

> >> >

> >> >> Secondly not only we get charger type from extcon, but also in

> >> >> some scenarios we can get charger type from USB controller driver,

> >> >> USB type-c driver, pmic driver, we should also need one place to

> >> >> export the

> >> charger type.

> >> >

> >> > As I have said, all of these sources of information should feed

> >> > into the extcon.

> >> >

> >> > There are ultimately two possible sources of information about the

> >> > current available from the usb port.

> >> > One is the physical properties of the cable, such as resistance of

> >> > ID, any short between D+ and D- etc.  Being properties of the

> >> > cable, they should be reported through the extcon.

> >> >

> >> > The other is information gathered during the USB protocol handshake.

> >> > For USB2, this is the requested current of the profile that the

> >> > host activates.  This should be reported though the USB gadget device.

> >> >

> >> > I don't know how USB3 and/or type-C work but I would be surprised

> >> > if they don't fit into the two cases above.  If you think

> >> > otherwise, please surprise me.  I'm always keen to learn.

> >> >

> >> > If the extcon reports the type of cable detected, and the gadget

> >> > reports the result of any negotiation, then that is enough to

> >> > determine the charger type.  It doesn't need to be more convenient

> >> > than

> >> that.

> >>

> >> If we are all agree we did not need the USB charger, then we can add

> >> 'current' attribute of USB gadget device.

> >> Thanks for your suggestion.

> >>

> >> --

> >> Baolin.wang

> >> Best Regards

> 

> 

> 

> --

> Baolin.wang

> Best Regards

(Exiting) Baolin Wang March 9, 2017, 11:22 a.m. UTC | #5

On 9 March 2017 at 18:34, Jun Li <[e-mail]> wrote:
>
>
>> -----Original Message-----
>> From: Baolin Wang [mailto:[e-mail]]
>> Sent: Thursday, March 09, 2017 2:11 PM
>> To: Jun Li <[e-mail]>
>> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH
>> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry
>> Eremin-Solenikov <[e-mail]>; David Woodhouse
>> <[e-mail]>; [e-mail]; Marek Szyprowski
>> <[e-mail]>; Ruslan Bilovol <[e-mail]>;
>> Peter Chen <[e-mail]>; Alan Stern
>> <[e-mail]>; [e-mail]; Yoshihiro Shimoda
>> <[e-mail]>; Lee Jones <[e-mail]>;
>> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;
>> Charles Keepax <[e-mail]>;
>> [e-mail]; Linux PM list <linux-
>> [e-mail]>; USB <[e-mail]>; device-
>> [e-mail]; LKML <[e-mail]>
>> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with
>> the usb gadget power negotation
>>
>> Hi,
>>
>> On 9 March 2017 at 09:50, Jun Li <[e-mail]> wrote:
>> > Hi,
>> >
>> >> -----Original Message-----
>> >> From: Baolin Wang [mailto:[e-mail]]
>> >> Sent: Tuesday, March 07, 2017 5:39 PM
>> >> To: NeilBrown <[e-mail]>
>> >> Cc: Felipe Balbi <[e-mail]>; Greg KH
>> >> <[e-mail]>; Sebastian Reichel <[e-mail]>;
>> >> Dmitry Eremin-Solenikov <[e-mail]>; David Woodhouse
>> >> <[e-mail]>; [e-mail]; Jun Li <[e-mail]>;
>> >> Marek Szyprowski <[e-mail]>; Ruslan Bilovol
>> >> <[e-mail]>; Peter Chen <[e-mail]>;
>> >> Alan Stern <[e-mail]>; [e-mail];
>> >> Yoshihiro Shimoda <[e-mail]>; Lee Jones
>> >> <[e-mail]>; Mark Brown <[e-mail]>; John Stultz
>> >> <[e-mail]>; Charles Keepax
>> >> <[e-mail]>;
>> >> [e-mail]; Linux PM list <linux-
>> >> [e-mail]>; USB <[e-mail]>; device-
>> >> [e-mail]; LKML
>> >> <[e-mail]>
>> >> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal
>> >> with the usb gadget power negotation
>> >>
>> >> On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:
>> >> > On Mon, Feb 20 2017, Baolin Wang wrote:
>> >> >
>> >> >> Currently the Linux kernel does not provide any standard
>> >> >> integration of this feature that integrates the USB subsystem with
>> >> >> the system power regulation provided by PMICs meaning that either
>> >> >> vendors must add this in their kernels or USB gadget devices based
>> >> >> on Linux (such as mobile phones) may not behave as they should.
>> >> >> Thus provide a
>> >> standard framework for doing this in kernel.
>> >> >>
>> >> >> Now introduce one user with wm831x_power to support and test the
>> >> >> usb
>> >> charger.
>> >> >> Another user introduced to support charger detection by Jun Li:
>> >> >> https://www.spinics.net/lists/linux-usb/msg139425.html
>> >> >> Moreover there may be other potential users will use it in future.
>> >> >>
>> >> >> 1. Before v19 patchset we've fixed below issues in extcon
>> >> >> subsystem and usb phy driver, now all were merged. (Thanks for
>> >> >> Neil's
>> >> >> suggestion)
>> >> >> (1) Have fixed the inconsistencies with USB connector types in
>> >> >> extcon subsystem by following links:
>> >> >> https://lkml.org/lkml/2016/12/21/13
>> >> >> https://lkml.org/lkml/2016/12/21/15
>> >> >> https://lkml.org/lkml/2016/12/21/79
>> >> >> https://lkml.org/lkml/2017/1/3/13
>> >> >>
>> >> >> (2) Instead of using 'set_power' callback in phy drivers, we will
>> >> >> introduce USB charger to set PMIC current drawn from USB
>> >> >> configuration, moreover some 'set_power' callbacks did not
>> >> >> implement anything to set PMIC current, thus remove them by
>> following links:
>> >> >> https://lkml.org/lkml/2017/1/18/436
>> >> >> https://lkml.org/lkml/2017/1/18/439
>> >> >> https://lkml.org/lkml/2017/1/18/438
>> >> >> Now only two phy drivers (phy-isp1301-omap.c and
>> >> >> phy-gpio-vbus-usb.c) still used 'set_power' callback to set
>> >> >> current, we can remove them in future. (I have no platform with
>> >> >> enabling these two phy drivers, so I can not test them if I
>> >> >> converted 'set_power' callback to USB
>> >> >> charger.)
>> >> >>
>> >> >> 2. Some issues pointed by Neil Brown were sill kept in this v19
>> >> >> patchset, and I expalined each issue and may be need discuss again:
>> >> >> (1) Change all usb phys to register an extcon and to send
>> >> >> appropriate
>> >> notifications.
>> >> >> Firstly, now only 3 USB phy drivers (phy-qcom-8x16-usb.c,
>> >> >> phy-omap-otg.c and
>> >> >> phy-msm-usb.c) had registered an extcon, mostly did not. I can not
>> >> >> change all usb phys to register an extcon, since there are no
>> >> >> extcon device to register for these different phy drivers.
>> >> >
>> >> > You don't have to change every driver.  You just need to make it
>> >> > easy and obvious how to change drivers in a consistent coherent way.
>> >> > For a start you would add a 'struct extcon_dev' to 'struct
>> >> > usb_phy', and possibly add or extend some 'static inline's in
>> >> > linux/usb/phy.h to send notification on that extcon (if it is non-NULL).
>> >> > e.g. usb_phy_vbus_on() could send an extcon notification.
>> >> >
>> >> > Then any phy driver which adds support for setting phy->extcon_dev
>> >> > appropriately, immediately gets the relevant notifications sent.
>> >>
>> >> OK. We can make these extcon related code into phy common part.
>> >>
>> >
>> > Will generic phy need add extcon as well?
>>
>> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which will be common
>> code.
>>
>
> I mean the common code need add 'struct extcon_dev' into both 'struct phy' and
> 'struct usb_phy', right? as some/new usb phy use that generic phy driver.

Ah, you remind me. Seems we need also add one 'struct extcon_dev' into
'struct phy'.

>> >
>> >> >
>> >> >> Secondly, I also agreed with Peter's comments: Not only USB PHY to
>> >> >> register an extcon, but also for the drivers which can detect USB
>> >> >> charger type, it may be USB controller driver, USB type-c driver,
>> >> >> pmic driver, and these drivers may not have an extcon device since
>> >> >> the internal part can finish the vbus detect.
>> >> >
>> >> > Whichever part can detect vbus, the driver for that part must be
>> >> > able to find the extcon and trigger a notification.
>> >> > Maybe one part can detect VBUS, another can measure the resistance
>> >> > on ID and a third can work through the state machine to determine
>> >> > if D+ and D- are shorted together.
>> >> > Somehow these three need to work together to determine what is
>> >> plugged
>> >> > in to the external connection port.  Somewhere there much an 'extcon'
>> >> > device which represents that port and which the three devices can
>> >> > find and can interact with.
>> >> > I think it makes sense for the usb_phy to be the connection point.
>> >> > Each of the devices can get to the phy, and the phy can get to the
>> extcon.
>> >> > It doesn't matter very much if the usb phy driver creates the
>> >> > extcon, or if something else creates the extcon and the phy driver
>> >> > performs a lookup to find it (e.g. based on devicetree info).
>> >> >
>> >> > The point is that there is obviously an external physical
>> >> > connection, and so there should be an 'extcon' device that represents it.
>> >>
>> >> Peter & Jun, is it OK for you every phy has one extcon device to
>> >> receive VBUS notification, especially for detecting the charger type by
>> software?
>> >>
>> >
>> > My understanding is phy/usb_phy as the connection point, will send the
>> > notification to PMIC driver which actually control the charge current,
>> > also this will be done in your common framework, right?
>>
>> Not in USB charger framework. If we are all agree every usb_phy can register
>> one extcon device, can get correct charger type and send out correct
>> vbus_draw information, then we don't need USB charger framework as Neil
>> suggested. So this will be okay for your case (especially for detecting the
>> charger type by software) ?
>
> In my case, charger detection is done by controller driver and I need do charger
> type detection internally, and only pass the current draw info via phy which will
> send out, this seems ok for me, but I think it will be good if you or someone can
> show us an example user based on the design Neil suggested.
> Will you work out that common code if this USB charger framework is not needed?

I will add  a 'struct extcon_dev*' in 'struct usb_phy' and struct
phy“. Others are already ready if everyone has no complain about
current design, except my one concern. (I am afraid if it is enough to
send out vbus draw information from USB phy driver, for example you
will miss super speed (900mA), which need get the speed information
from gadget driver.)

>> >> >
>> >> >>
>> >> >> (2) Change the notifier of usb_phy to be used consistently.
>> >> >> Now only 3 phy drivers (phy-generic.c, phy-ab8500-usb.c and
>> >> >> phy-gpio-vbus-usb.c) used the notifier of usb_phy. phy-generic.c
>> >> >> and phy-gpio-vbus-usb.c were used to send out the connect events,
>> >> >> and phy-ab8500-usb.c also was used to send out the MUSB connect
>> events.
>> >> >> There are no phy drivers will notify 'vbus_draw' information by
>> >> >> the
>> >> notifier of usb_phy, which was used consistently now.
>> >> >> Moreover it is difficult to change the notifier of usb_phy to be
>> >> >> used only to communicate the 'vbus_draw' information, since we
>> >> >> need to refactor and test these related phy drivers, power drivers
>> >> >> or some mfd drivers, which is a huge workload.
>> >> >
>> >> > You missed drivers/usb/musb/omap2430.c in you list, but that hardly
>> >> > matters.
>> >>
>> >> But it did not use the notifier of usb_phy.
>> >>
>> >> > phy-ab8500-usb.c appears to send vbus_draw information.
>> >>
>> >> Users will not use the vbus_draw information send from
>> >> phy-ab8500-usb.c
>> >>
>> >> >
>> >> > I understand your reluctance to change drivers that you cannot test.
>> >> > An alternative it do change all the
>> >> >   atomic_notifier_call_chain(.*notifier,
>> >> > calls that don't pass a pointer to vbus_draw to pass NULL, and to
>> >> > declare the passing of NULL to be deprecated (so hopefully people
>> >> > won't use it in new code).
>> >> > Then any notification callback that expects a current can just
>> >> > ignore calls where the pointer is NULL.
>> >>
>> >> I am afraid if it is enough to send out vbus draw information from
>> >> USB phy driver, for example you will miss super speed (900mA), which
>> >> need get the speed information from gadget driver.
>> >>
>> >> >
>> >> > The one difficulty with this is drivers/usb/gadget/udc/pxa27x_udc.c
>> >> > It is the only driver which expects a 'gadget', and it doesn't
>> >> > really need to as it already knows the gadget.
>> >> > The patch below fixes this.
>> >> > With that in place, phy-generic and phy-gpio-vbus-usb can be
>> >> > changed to pass NULL.  When we can safely use the notifier to pass
>> >> > vbus_draw information uniformly.
>> >> >
>> >> >>
>> >> >> (3) Still keep charger_type_show() API.
>> >> >> Firstly I think we should combine all charger related information
>> >> >> into one place for users, which is convenient.
>> >> >
>> >> > convenience is very much a secondary issue.
>> >> >
>> >> >> Secondly not only we get charger type from extcon, but also in
>> >> >> some scenarios we can get charger type from USB controller driver,
>> >> >> USB type-c driver, pmic driver, we should also need one place to
>> >> >> export the
>> >> charger type.
>> >> >
>> >> > As I have said, all of these sources of information should feed
>> >> > into the extcon.
>> >> >
>> >> > There are ultimately two possible sources of information about the
>> >> > current available from the usb port.
>> >> > One is the physical properties of the cable, such as resistance of
>> >> > ID, any short between D+ and D- etc.  Being properties of the
>> >> > cable, they should be reported through the extcon.
>> >> >
>> >> > The other is information gathered during the USB protocol handshake.
>> >> > For USB2, this is the requested current of the profile that the
>> >> > host activates.  This should be reported though the USB gadget device.
>> >> >
>> >> > I don't know how USB3 and/or type-C work but I would be surprised
>> >> > if they don't fit into the two cases above.  If you think
>> >> > otherwise, please surprise me.  I'm always keen to learn.
>> >> >
>> >> > If the extcon reports the type of cable detected, and the gadget
>> >> > reports the result of any negotiation, then that is enough to
>> >> > determine the charger type.  It doesn't need to be more convenient
>> >> > than
>> >> that.
>> >>
>> >> If we are all agree we did not need the USB charger, then we can add
>> >> 'current' attribute of USB gadget device.
>> >> Thanks for your suggestion.
>> >>
>> >> --
>> >> Baolin.wang
>> >> Best Regards
>>
>>
>>
>> --
>> Baolin.wang
>> Best Regards

Jun Li March 10, 2017, 6:30 a.m. UTC | #6

> -----Original Message-----

> From: Baolin Wang [mailto:[e-mail]]

> Sent: Thursday, March 09, 2017 7:23 PM

> To: Jun Li <[e-mail]>

> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH

> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry

> Eremin-Solenikov <[e-mail]>; David Woodhouse

> <[e-mail]>; [e-mail]; Marek Szyprowski

> <[e-mail]>; Ruslan Bilovol <[e-mail]>;

> Peter Chen <[e-mail]>; Alan Stern

> <[e-mail]>; [e-mail]; Yoshihiro Shimoda

> <[e-mail]>; Lee Jones <[e-mail]>;

> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;

> Charles Keepax <[e-mail]>;

> [e-mail]; Linux PM list <linux-

> [e-mail]>; USB <[e-mail]>; device-

> [e-mail]; LKML <[e-mail]>

> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with

> the usb gadget power negotation

> 

> On 9 March 2017 at 18:34, Jun Li <[e-mail]> wrote:

> >

> >

> >> -----Original Message-----

> >> From: Baolin Wang [mailto:[e-mail]]

> >> Sent: Thursday, March 09, 2017 2:11 PM

> >> To: Jun Li <[e-mail]>

> >> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg

> >> KH <[e-mail]>; Sebastian Reichel <[e-mail]>;

> >> Dmitry Eremin-Solenikov <[e-mail]>; David Woodhouse

> >> <[e-mail]>; [e-mail]; Marek Szyprowski

> >> <[e-mail]>; Ruslan Bilovol

> >> <[e-mail]>; Peter Chen <[e-mail]>;

> >> Alan Stern <[e-mail]>; [e-mail];

> >> Yoshihiro Shimoda <[e-mail]>; Lee Jones

> >> <[e-mail]>; Mark Brown <[e-mail]>; John Stultz

> >> <[e-mail]>; Charles Keepax

> >> <[e-mail]>;

> >> [e-mail]; Linux PM list <linux-

> >> [e-mail]>; USB <[e-mail]>; device-

> >> [e-mail]; LKML

> >> <[e-mail]>

> >> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal

> >> with the usb gadget power negotation

> >>

> >> Hi,

> >>

> >> On 9 March 2017 at 09:50, Jun Li <[e-mail]> wrote:

> >> > Hi,

> >> >

> >> >> -----Original Message-----

> >> >> From: Baolin Wang [mailto:[e-mail]]

> >> >> Sent: Tuesday, March 07, 2017 5:39 PM

> >> >> To: NeilBrown <[e-mail]>

> >> >> Cc: Felipe Balbi <[e-mail]>; Greg KH

> >> >> <[e-mail]>; Sebastian Reichel <[e-mail]>;

> >> >> Dmitry Eremin-Solenikov <[e-mail]>; David

> Woodhouse

> >> >> <[e-mail]>; [e-mail]; Jun Li <[e-mail]>;

> >> >> Marek Szyprowski <[e-mail]>; Ruslan Bilovol

> >> >> <[e-mail]>; Peter Chen

> <[e-mail]>;

> >> >> Alan Stern <[e-mail]>; [e-mail];

> >> >> Yoshihiro Shimoda <[e-mail]>; Lee Jones

> >> >> <[e-mail]>; Mark Brown <[e-mail]>; John

> >> >> Stultz <[e-mail]>; Charles Keepax

> >> >> <[e-mail]>;

> >> >> [e-mail]; Linux PM list <linux-

> >> >> [e-mail]>; USB <[e-mail]>; device-

> >> >> [e-mail]; LKML

> >> >> <[e-mail]>

> >> >> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to

> >> >> deal with the usb gadget power negotation

> >> >>

> >> >> On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:

> >> >> > On Mon, Feb 20 2017, Baolin Wang wrote:

> >> >> >

> >> >> >> Currently the Linux kernel does not provide any standard

> >> >> >> integration of this feature that integrates the USB subsystem

> >> >> >> with the system power regulation provided by PMICs meaning that

> >> >> >> either vendors must add this in their kernels or USB gadget

> >> >> >> devices based on Linux (such as mobile phones) may not behave as

> they should.

> >> >> >> Thus provide a

> >> >> standard framework for doing this in kernel.

> >> >> >>

> >> >> >> Now introduce one user with wm831x_power to support and test

> >> >> >> the usb

> >> >> charger.

> >> >> >> Another user introduced to support charger detection by Jun Li:

> >> >> >> https://www.spinics.net/lists/linux-usb/msg139425.html

> >> >> >> Moreover there may be other potential users will use it in future.

> >> >> >>

> >> >> >> 1. Before v19 patchset we've fixed below issues in extcon

> >> >> >> subsystem and usb phy driver, now all were merged. (Thanks for

> >> >> >> Neil's

> >> >> >> suggestion)

> >> >> >> (1) Have fixed the inconsistencies with USB connector types in

> >> >> >> extcon subsystem by following links:

> >> >> >> https://lkml.org/lkml/2016/12/21/13

> >> >> >> https://lkml.org/lkml/2016/12/21/15

> >> >> >> https://lkml.org/lkml/2016/12/21/79

> >> >> >> https://lkml.org/lkml/2017/1/3/13

> >> >> >>

> >> >> >> (2) Instead of using 'set_power' callback in phy drivers, we

> >> >> >> will introduce USB charger to set PMIC current drawn from USB

> >> >> >> configuration, moreover some 'set_power' callbacks did not

> >> >> >> implement anything to set PMIC current, thus remove them by

> >> following links:

> >> >> >> https://lkml.org/lkml/2017/1/18/436

> >> >> >> https://lkml.org/lkml/2017/1/18/439

> >> >> >> https://lkml.org/lkml/2017/1/18/438

> >> >> >> Now only two phy drivers (phy-isp1301-omap.c and

> >> >> >> phy-gpio-vbus-usb.c) still used 'set_power' callback to set

> >> >> >> current, we can remove them in future. (I have no platform with

> >> >> >> enabling these two phy drivers, so I can not test them if I

> >> >> >> converted 'set_power' callback to USB

> >> >> >> charger.)

> >> >> >>

> >> >> >> 2. Some issues pointed by Neil Brown were sill kept in this v19

> >> >> >> patchset, and I expalined each issue and may be need discuss again:

> >> >> >> (1) Change all usb phys to register an extcon and to send

> >> >> >> appropriate

> >> >> notifications.

> >> >> >> Firstly, now only 3 USB phy drivers (phy-qcom-8x16-usb.c,

> >> >> >> phy-omap-otg.c and

> >> >> >> phy-msm-usb.c) had registered an extcon, mostly did not. I can

> >> >> >> not change all usb phys to register an extcon, since there are

> >> >> >> no extcon device to register for these different phy drivers.

> >> >> >

> >> >> > You don't have to change every driver.  You just need to make it

> >> >> > easy and obvious how to change drivers in a consistent coherent way.

> >> >> > For a start you would add a 'struct extcon_dev' to 'struct

> >> >> > usb_phy', and possibly add or extend some 'static inline's in

> >> >> > linux/usb/phy.h to send notification on that extcon (if it is non-NULL).

> >> >> > e.g. usb_phy_vbus_on() could send an extcon notification.

> >> >> >

> >> >> > Then any phy driver which adds support for setting

> >> >> > phy->extcon_dev appropriately, immediately gets the relevant

> notifications sent.

> >> >>

> >> >> OK. We can make these extcon related code into phy common part.

> >> >>

> >> >

> >> > Will generic phy need add extcon as well?

> >>

> >> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which will

> >> be common code.

> >>

> >

> > I mean the common code need add 'struct extcon_dev' into both 'struct

> > phy' and 'struct usb_phy', right? as some/new usb phy use that generic phy

> driver.

> 

> Ah, you remind me. Seems we need also add one 'struct extcon_dev' into

> 'struct phy'.

> 

> >> >

> >> >> >

> >> >> >> Secondly, I also agreed with Peter's comments: Not only USB PHY

> >> >> >> to register an extcon, but also for the drivers which can

> >> >> >> detect USB charger type, it may be USB controller driver, USB

> >> >> >> type-c driver, pmic driver, and these drivers may not have an

> >> >> >> extcon device since the internal part can finish the vbus detect.

> >> >> >

> >> >> > Whichever part can detect vbus, the driver for that part must be

> >> >> > able to find the extcon and trigger a notification.

> >> >> > Maybe one part can detect VBUS, another can measure the

> >> >> > resistance on ID and a third can work through the state machine

> >> >> > to determine if D+ and D- are shorted together.

> >> >> > Somehow these three need to work together to determine what is

> >> >> plugged

> >> >> > in to the external connection port.  Somewhere there much an

> 'extcon'

> >> >> > device which represents that port and which the three devices

> >> >> > can find and can interact with.

> >> >> > I think it makes sense for the usb_phy to be the connection point.

> >> >> > Each of the devices can get to the phy, and the phy can get to

> >> >> > the

> >> extcon.

> >> >> > It doesn't matter very much if the usb phy driver creates the

> >> >> > extcon, or if something else creates the extcon and the phy

> >> >> > driver performs a lookup to find it (e.g. based on devicetree info).

> >> >> >

> >> >> > The point is that there is obviously an external physical

> >> >> > connection, and so there should be an 'extcon' device that

> represents it.

> >> >>

> >> >> Peter & Jun, is it OK for you every phy has one extcon device to

> >> >> receive VBUS notification, especially for detecting the charger

> >> >> type by

> >> software?

> >> >>

> >> >

> >> > My understanding is phy/usb_phy as the connection point, will send

> >> > the notification to PMIC driver which actually control the charge

> >> > current, also this will be done in your common framework, right?

> >>

> >> Not in USB charger framework. If we are all agree every usb_phy can

> >> register one extcon device, can get correct charger type and send out

> >> correct vbus_draw information, then we don't need USB charger

> >> framework as Neil suggested. So this will be okay for your case

> >> (especially for detecting the charger type by software) ?

> >

> > In my case, charger detection is done by controller driver and I need

> > do charger type detection internally, and only pass the current draw

> > info via phy which will send out, this seems ok for me, but I think it

> > will be good if you or someone can show us an example user based on the

> design Neil suggested.

> > Will you work out that common code if this USB charger framework is not

> needed?

> 

> I will add  a 'struct extcon_dev*' in 'struct usb_phy' and struct phy“. Others

> are already ready if everyone has no complain about current design, except


Only adding extcon_dev into usb_phy/phy  and all others are ready?
My understanding you will also do:
- We need find a central place to send the notification(phy common part).
- If the extcon_dev is directly added in usb_phy/phy, PMIC needs some API to findup it.

> my one concern. (I am afraid if it is enough to send out vbus draw

> information from USB phy driver, for example you will miss super speed

> (900mA), which need get the speed information from gadget driver.)

> 


Can we handle this in USB(so has super speed information) and just send out
900mA directly?

Li Jun

(Exiting) Baolin Wang March 10, 2017, 7:15 a.m. UTC | #7

On 10 March 2017 at 14:30, Jun Li <[e-mail]> wrote:
>> >> >
>> >> > Will generic phy need add extcon as well?
>> >>
>> >> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which will
>> >> be common code.
>> >>
>> >
>> > I mean the common code need add 'struct extcon_dev' into both 'struct
>> > phy' and 'struct usb_phy', right? as some/new usb phy use that generic phy
>> driver.
>>
>> Ah, you remind me. Seems we need also add one 'struct extcon_dev' into
>> 'struct phy'.
>>
>> >> >
>> >> >> >
>> >> >> >> Secondly, I also agreed with Peter's comments: Not only USB PHY
>> >> >> >> to register an extcon, but also for the drivers which can
>> >> >> >> detect USB charger type, it may be USB controller driver, USB
>> >> >> >> type-c driver, pmic driver, and these drivers may not have an
>> >> >> >> extcon device since the internal part can finish the vbus detect.
>> >> >> >
>> >> >> > Whichever part can detect vbus, the driver for that part must be
>> >> >> > able to find the extcon and trigger a notification.
>> >> >> > Maybe one part can detect VBUS, another can measure the
>> >> >> > resistance on ID and a third can work through the state machine
>> >> >> > to determine if D+ and D- are shorted together.
>> >> >> > Somehow these three need to work together to determine what is
>> >> >> plugged
>> >> >> > in to the external connection port.  Somewhere there much an
>> 'extcon'
>> >> >> > device which represents that port and which the three devices
>> >> >> > can find and can interact with.
>> >> >> > I think it makes sense for the usb_phy to be the connection point.
>> >> >> > Each of the devices can get to the phy, and the phy can get to
>> >> >> > the
>> >> extcon.
>> >> >> > It doesn't matter very much if the usb phy driver creates the
>> >> >> > extcon, or if something else creates the extcon and the phy
>> >> >> > driver performs a lookup to find it (e.g. based on devicetree info).
>> >> >> >
>> >> >> > The point is that there is obviously an external physical
>> >> >> > connection, and so there should be an 'extcon' device that
>> represents it.
>> >> >>
>> >> >> Peter & Jun, is it OK for you every phy has one extcon device to
>> >> >> receive VBUS notification, especially for detecting the charger
>> >> >> type by
>> >> software?
>> >> >>
>> >> >
>> >> > My understanding is phy/usb_phy as the connection point, will send
>> >> > the notification to PMIC driver which actually control the charge
>> >> > current, also this will be done in your common framework, right?
>> >>
>> >> Not in USB charger framework. If we are all agree every usb_phy can
>> >> register one extcon device, can get correct charger type and send out
>> >> correct vbus_draw information, then we don't need USB charger
>> >> framework as Neil suggested. So this will be okay for your case
>> >> (especially for detecting the charger type by software) ?
>> >
>> > In my case, charger detection is done by controller driver and I need
>> > do charger type detection internally, and only pass the current draw
>> > info via phy which will send out, this seems ok for me, but I think it
>> > will be good if you or someone can show us an example user based on the
>> design Neil suggested.
>> > Will you work out that common code if this USB charger framework is not
>> needed?
>>
>> I will add  a 'struct extcon_dev*' in 'struct usb_phy' and struct phy“. Others
>> are already ready if everyone has no complain about current design, except
>
> Only adding extcon_dev into usb_phy/phy  and all others are ready?
> My understanding you will also do:
> - We need find a central place to send the notification(phy common part).

That will include these implementation when adding extcon_dev.

> - If the extcon_dev is directly added in usb_phy/phy, PMIC needs some API to findup it.

PMIC can find extcon device by phandle.

>
>> my one concern. (I am afraid if it is enough to send out vbus draw
>> information from USB phy driver, for example you will miss super speed
>> (900mA), which need get the speed information from gadget driver.)
>>
>
> Can we handle this in USB(so has super speed information) and just send out
> 900mA directly?

From Neil's suggestion, we only have one place to send out current
information from usb phy, so I have this concern and doubt if we still
need the USB charger framework.

Jun Li March 10, 2017, 8:27 a.m. UTC | #8

Hi

> -----Original Message-----

> From: Baolin Wang [mailto:[e-mail]]

> Sent: Friday, March 10, 2017 3:15 PM

> To: Jun Li <[e-mail]>

> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH

> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry

> Eremin-Solenikov <[e-mail]>; David Woodhouse

> <[e-mail]>; [e-mail]; Marek Szyprowski

> <[e-mail]>; Ruslan Bilovol <[e-mail]>;

> Peter Chen <[e-mail]>; Alan Stern

> <[e-mail]>; [e-mail]; Yoshihiro Shimoda

> <[e-mail]>; Lee Jones <[e-mail]>;

> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;

> Charles Keepax <[e-mail]>;

> [e-mail]; Linux PM list <linux-

> [e-mail]>; USB <[e-mail]>; device-

> [e-mail]; LKML <[e-mail]>

> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with

> the usb gadget power negotation

> 

> On 10 March 2017 at 14:30, Jun Li <[e-mail]> wrote:

> >> >> >

> >> >> > Will generic phy need add extcon as well?

> >> >>

> >> >> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which

> >> >> will be common code.

> >> >>

> >> >

> >> > I mean the common code need add 'struct extcon_dev' into both

> >> > 'struct phy' and 'struct usb_phy', right? as some/new usb phy use

> >> > that generic phy

> >> driver.

> >>

> >> Ah, you remind me. Seems we need also add one 'struct extcon_dev'

> >> into 'struct phy'.

> >>

> >> >> >

> >> >> >> >

> >> >> >> >> Secondly, I also agreed with Peter's comments: Not only USB

> >> >> >> >> PHY to register an extcon, but also for the drivers which

> >> >> >> >> can detect USB charger type, it may be USB controller

> >> >> >> >> driver, USB type-c driver, pmic driver, and these drivers

> >> >> >> >> may not have an extcon device since the internal part can finish

> the vbus detect.

> >> >> >> >

> >> >> >> > Whichever part can detect vbus, the driver for that part must

> >> >> >> > be able to find the extcon and trigger a notification.

> >> >> >> > Maybe one part can detect VBUS, another can measure the

> >> >> >> > resistance on ID and a third can work through the state

> >> >> >> > machine to determine if D+ and D- are shorted together.

> >> >> >> > Somehow these three need to work together to determine what

> >> >> >> > is

> >> >> >> plugged

> >> >> >> > in to the external connection port.  Somewhere there much an

> >> 'extcon'

> >> >> >> > device which represents that port and which the three devices

> >> >> >> > can find and can interact with.

> >> >> >> > I think it makes sense for the usb_phy to be the connection point.

> >> >> >> > Each of the devices can get to the phy, and the phy can get

> >> >> >> > to the

> >> >> extcon.

> >> >> >> > It doesn't matter very much if the usb phy driver creates the

> >> >> >> > extcon, or if something else creates the extcon and the phy

> >> >> >> > driver performs a lookup to find it (e.g. based on devicetree info).

> >> >> >> >

> >> >> >> > The point is that there is obviously an external physical

> >> >> >> > connection, and so there should be an 'extcon' device that

> >> represents it.

> >> >> >>

> >> >> >> Peter & Jun, is it OK for you every phy has one extcon device

> >> >> >> to receive VBUS notification, especially for detecting the

> >> >> >> charger type by

> >> >> software?

> >> >> >>

> >> >> >

> >> >> > My understanding is phy/usb_phy as the connection point, will

> >> >> > send the notification to PMIC driver which actually control the

> >> >> > charge current, also this will be done in your common framework,

> right?

> >> >>

> >> >> Not in USB charger framework. If we are all agree every usb_phy

> >> >> can register one extcon device, can get correct charger type and

> >> >> send out correct vbus_draw information, then we don't need USB

> >> >> charger framework as Neil suggested. So this will be okay for your

> >> >> case (especially for detecting the charger type by software) ?

> >> >

> >> > In my case, charger detection is done by controller driver and I

> >> > need do charger type detection internally, and only pass the

> >> > current draw info via phy which will send out, this seems ok for

> >> > me, but I think it will be good if you or someone can show us an

> >> > example user based on the

> >> design Neil suggested.

> >> > Will you work out that common code if this USB charger framework is

> >> > not

> >> needed?

> >>

> >> I will add  a 'struct extcon_dev*' in 'struct usb_phy' and struct

> >> phy“. Others are already ready if everyone has no complain about

> >> current design, except

> >

> > Only adding extcon_dev into usb_phy/phy  and all others are ready?

> > My understanding you will also do:

> > - We need find a central place to send the notification(phy common part).

> 

> That will include these implementation when adding extcon_dev.

> 


OK, thanks.

> > - If the extcon_dev is directly added in usb_phy/phy, PMIC needs some

> API to findup it.

> 

> PMIC can find extcon device by phandle.


extcon_dev(not a reference pointer) is directly added in usb_phy/phy, not via devicetree,
how PMIC find it by phandle?
 
> 

> >

> >> my one concern. (I am afraid if it is enough to send out vbus draw

> >> information from USB phy driver, for example you will miss super

> >> speed (900mA), which need get the speed information from gadget

> >> driver.)

> >>

> >

> > Can we handle this in USB(so has super speed information) and just

> > send out 900mA directly?

> 

> From Neil's suggestion, we only have one place to send out current

> information from usb phy, so I have this concern and doubt if we still need

> the USB charger framework.


So if put it in phy/usb_phy, this is a problem, that only one place should have
the infor of both speed and usb state, how about put it at usb_gadget, then,
e.g. send the notification in usb_gadget_vbus_connect()?

Li Jun

> 

> --

> Baolin.wang

> Best Regards

(Exiting) Baolin Wang March 10, 2017, 10:52 a.m. UTC | #9

On 10 March 2017 at 16:27, Jun Li <[e-mail]> wrote:
> Hi
>
>> -----Original Message-----
>> From: Baolin Wang [mailto:[e-mail]]
>> Sent: Friday, March 10, 2017 3:15 PM
>> To: Jun Li <[e-mail]>
>> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH
>> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry
>> Eremin-Solenikov <[e-mail]>; David Woodhouse
>> <[e-mail]>; [e-mail]; Marek Szyprowski
>> <[e-mail]>; Ruslan Bilovol <[e-mail]>;
>> Peter Chen <[e-mail]>; Alan Stern
>> <[e-mail]>; [e-mail]; Yoshihiro Shimoda
>> <[e-mail]>; Lee Jones <[e-mail]>;
>> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;
>> Charles Keepax <[e-mail]>;
>> [e-mail]; Linux PM list <linux-
>> [e-mail]>; USB <[e-mail]>; device-
>> [e-mail]; LKML <[e-mail]>
>> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with
>> the usb gadget power negotation
>>
>> On 10 March 2017 at 14:30, Jun Li <[e-mail]> wrote:
>> >> >> >
>> >> >> > Will generic phy need add extcon as well?
>> >> >>
>> >> >> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which
>> >> >> will be common code.
>> >> >>
>> >> >
>> >> > I mean the common code need add 'struct extcon_dev' into both
>> >> > 'struct phy' and 'struct usb_phy', right? as some/new usb phy use
>> >> > that generic phy
>> >> driver.
>> >>
>> >> Ah, you remind me. Seems we need also add one 'struct extcon_dev'
>> >> into 'struct phy'.
>> >>
>> >> >> >
>> >> >> >> >
>> >> >> >> >> Secondly, I also agreed with Peter's comments: Not only USB
>> >> >> >> >> PHY to register an extcon, but also for the drivers which
>> >> >> >> >> can detect USB charger type, it may be USB controller
>> >> >> >> >> driver, USB type-c driver, pmic driver, and these drivers
>> >> >> >> >> may not have an extcon device since the internal part can finish
>> the vbus detect.
>> >> >> >> >
>> >> >> >> > Whichever part can detect vbus, the driver for that part must
>> >> >> >> > be able to find the extcon and trigger a notification.
>> >> >> >> > Maybe one part can detect VBUS, another can measure the
>> >> >> >> > resistance on ID and a third can work through the state
>> >> >> >> > machine to determine if D+ and D- are shorted together.
>> >> >> >> > Somehow these three need to work together to determine what
>> >> >> >> > is
>> >> >> >> plugged
>> >> >> >> > in to the external connection port.  Somewhere there much an
>> >> 'extcon'
>> >> >> >> > device which represents that port and which the three devices
>> >> >> >> > can find and can interact with.
>> >> >> >> > I think it makes sense for the usb_phy to be the connection point.
>> >> >> >> > Each of the devices can get to the phy, and the phy can get
>> >> >> >> > to the
>> >> >> extcon.
>> >> >> >> > It doesn't matter very much if the usb phy driver creates the
>> >> >> >> > extcon, or if something else creates the extcon and the phy
>> >> >> >> > driver performs a lookup to find it (e.g. based on devicetree info).
>> >> >> >> >
>> >> >> >> > The point is that there is obviously an external physical
>> >> >> >> > connection, and so there should be an 'extcon' device that
>> >> represents it.
>> >> >> >>
>> >> >> >> Peter & Jun, is it OK for you every phy has one extcon device
>> >> >> >> to receive VBUS notification, especially for detecting the
>> >> >> >> charger type by
>> >> >> software?
>> >> >> >>
>> >> >> >
>> >> >> > My understanding is phy/usb_phy as the connection point, will
>> >> >> > send the notification to PMIC driver which actually control the
>> >> >> > charge current, also this will be done in your common framework,
>> right?
>> >> >>
>> >> >> Not in USB charger framework. If we are all agree every usb_phy
>> >> >> can register one extcon device, can get correct charger type and
>> >> >> send out correct vbus_draw information, then we don't need USB
>> >> >> charger framework as Neil suggested. So this will be okay for your
>> >> >> case (especially for detecting the charger type by software) ?
>> >> >
>> >> > In my case, charger detection is done by controller driver and I
>> >> > need do charger type detection internally, and only pass the
>> >> > current draw info via phy which will send out, this seems ok for
>> >> > me, but I think it will be good if you or someone can show us an
>> >> > example user based on the
>> >> design Neil suggested.
>> >> > Will you work out that common code if this USB charger framework is
>> >> > not
>> >> needed?
>> >>
>> >> I will add  a 'struct extcon_dev*' in 'struct usb_phy' and struct
>> >> phy“. Others are already ready if everyone has no complain about
>> >> current design, except
>> >
>> > Only adding extcon_dev into usb_phy/phy  and all others are ready?
>> > My understanding you will also do:
>> > - We need find a central place to send the notification(phy common part).
>>
>> That will include these implementation when adding extcon_dev.
>>
>
> OK, thanks.
>
>> > - If the extcon_dev is directly added in usb_phy/phy, PMIC needs some
>> API to findup it.
>>
>> PMIC can find extcon device by phandle.
>
> extcon_dev(not a reference pointer) is directly added in usb_phy/phy, not via devicetree,
> how PMIC find it by phandle?

From my understanding, here we should add one pointer (extcon_dev *),
since usb phy is not one external connect device.

>
>>
>> >
>> >> my one concern. (I am afraid if it is enough to send out vbus draw
>> >> information from USB phy driver, for example you will miss super
>> >> speed (900mA), which need get the speed information from gadget
>> >> driver.)
>> >>
>> >
>> > Can we handle this in USB(so has super speed information) and just
>> > send out 900mA directly?
>>
>> From Neil's suggestion, we only have one place to send out current
>> information from usb phy, so I have this concern and doubt if we still need
>> the USB charger framework.
>
> So if put it in phy/usb_phy, this is a problem, that only one place should have
> the infor of both speed and usb state, how about put it at usb_gadget, then,
> e.g. send the notification in usb_gadget_vbus_connect()?

That is same what USB charger did, from this point, we need USB
charger to send out vbus draw information according to speed and usb
state. But I should listen to other guys suggestion. Peter and Felipe,
what do you think?

Jun Li March 13, 2017, 1:09 a.m. UTC | #10

Hi,

> -----Original Message-----

> From: Baolin Wang [mailto:[e-mail]]

> Sent: Friday, March 10, 2017 6:52 PM

> To: Jun Li <[e-mail]>

> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH

> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry

> Eremin-Solenikov <[e-mail]>; David Woodhouse

> <[e-mail]>; [e-mail]; Marek Szyprowski

> <[e-mail]>; Ruslan Bilovol <[e-mail]>;

> Peter Chen <[e-mail]>; Alan Stern

> <[e-mail]>; [e-mail]; Yoshihiro Shimoda

> <[e-mail]>; Lee Jones <[e-mail]>;

> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;

> Charles Keepax <[e-mail]>;

> [e-mail]; Linux PM list <linux-

> [e-mail]>; USB <[e-mail]>; device-

> [e-mail]; LKML <[e-mail]>

> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with

> the usb gadget power negotation

> 

> On 10 March 2017 at 16:27, Jun Li <[e-mail]> wrote:

> > Hi

> >

> >> -----Original Message-----

> >> From: Baolin Wang [mailto:[e-mail]]

> >> Sent: Friday, March 10, 2017 3:15 PM

> >> To: Jun Li <[e-mail]>

> >> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg

> >> KH <[e-mail]>; Sebastian Reichel <[e-mail]>;

> >> Dmitry Eremin-Solenikov <[e-mail]>; David Woodhouse

> >> <[e-mail]>; [e-mail]; Marek Szyprowski

> >> <[e-mail]>; Ruslan Bilovol

> >> <[e-mail]>; Peter Chen <[e-mail]>;

> >> Alan Stern <[e-mail]>; [e-mail];

> >> Yoshihiro Shimoda <[e-mail]>; Lee Jones

> >> <[e-mail]>; Mark Brown <[e-mail]>; John Stultz

> >> <[e-mail]>; Charles Keepax

> >> <[e-mail]>;

> >> [e-mail]; Linux PM list <linux-

> >> [e-mail]>; USB <[e-mail]>; device-

> >> [e-mail]; LKML

> >> <[e-mail]>

> >> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal

> >> with the usb gadget power negotation

> >>

> >> On 10 March 2017 at 14:30, Jun Li <[e-mail]> wrote:

> >> >> >> >

> >> >> >> > Will generic phy need add extcon as well?

> >> >> >>

> >> >> >> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which

> >> >> >> will be common code.

> >> >> >>

> >> >> >

> >> >> > I mean the common code need add 'struct extcon_dev' into both

> >> >> > 'struct phy' and 'struct usb_phy', right? as some/new usb phy

> >> >> > use that generic phy

> >> >> driver.

> >> >>

> >> >> Ah, you remind me. Seems we need also add one 'struct extcon_dev'

> >> >> into 'struct phy'.

> >> >>

> >> >> >> >

> >> >> >> >> >

> >> >> >> >> >> Secondly, I also agreed with Peter's comments: Not only

> >> >> >> >> >> USB PHY to register an extcon, but also for the drivers

> >> >> >> >> >> which can detect USB charger type, it may be USB

> >> >> >> >> >> controller driver, USB type-c driver, pmic driver, and

> >> >> >> >> >> these drivers may not have an extcon device since the

> >> >> >> >> >> internal part can finish

> >> the vbus detect.

> >> >> >> >> >

> >> >> >> >> > Whichever part can detect vbus, the driver for that part

> >> >> >> >> > must be able to find the extcon and trigger a notification.

> >> >> >> >> > Maybe one part can detect VBUS, another can measure the

> >> >> >> >> > resistance on ID and a third can work through the state

> >> >> >> >> > machine to determine if D+ and D- are shorted together.

> >> >> >> >> > Somehow these three need to work together to determine

> >> >> >> >> > what is

> >> >> >> >> plugged

> >> >> >> >> > in to the external connection port.  Somewhere there much

> >> >> >> >> > an

> >> >> 'extcon'

> >> >> >> >> > device which represents that port and which the three

> >> >> >> >> > devices can find and can interact with.

> >> >> >> >> > I think it makes sense for the usb_phy to be the connection

> point.

> >> >> >> >> > Each of the devices can get to the phy, and the phy can

> >> >> >> >> > get to the

> >> >> >> extcon.

> >> >> >> >> > It doesn't matter very much if the usb phy driver creates

> >> >> >> >> > the extcon, or if something else creates the extcon and

> >> >> >> >> > the phy driver performs a lookup to find it (e.g. based on

> devicetree info).

> >> >> >> >> >

> >> >> >> >> > The point is that there is obviously an external physical

> >> >> >> >> > connection, and so there should be an 'extcon' device that

> >> >> represents it.

> >> >> >> >>

> >> >> >> >> Peter & Jun, is it OK for you every phy has one extcon

> >> >> >> >> device to receive VBUS notification, especially for

> >> >> >> >> detecting the charger type by

> >> >> >> software?

> >> >> >> >>

> >> >> >> >

> >> >> >> > My understanding is phy/usb_phy as the connection point, will

> >> >> >> > send the notification to PMIC driver which actually control

> >> >> >> > the charge current, also this will be done in your common

> >> >> >> > framework,

> >> right?

> >> >> >>

> >> >> >> Not in USB charger framework. If we are all agree every usb_phy

> >> >> >> can register one extcon device, can get correct charger type

> >> >> >> and send out correct vbus_draw information, then we don't need

> >> >> >> USB charger framework as Neil suggested. So this will be okay

> >> >> >> for your case (especially for detecting the charger type by

> software) ?

> >> >> >

> >> >> > In my case, charger detection is done by controller driver and I

> >> >> > need do charger type detection internally, and only pass the

> >> >> > current draw info via phy which will send out, this seems ok for

> >> >> > me, but I think it will be good if you or someone can show us an

> >> >> > example user based on the

> >> >> design Neil suggested.

> >> >> > Will you work out that common code if this USB charger framework

> >> >> > is not

> >> >> needed?

> >> >>

> >> >> I will add  a 'struct extcon_dev*' in 'struct usb_phy' and struct

> >> >> phy“. Others are already ready if everyone has no complain about

> >> >> current design, except

> >> >

> >> > Only adding extcon_dev into usb_phy/phy  and all others are ready?

> >> > My understanding you will also do:

> >> > - We need find a central place to send the notification(phy common

> part).

> >>

> >> That will include these implementation when adding extcon_dev.

> >>

> >

> > OK, thanks.

> >

> >> > - If the extcon_dev is directly added in usb_phy/phy, PMIC needs

> >> > some

> >> API to findup it.

> >>

> >> PMIC can find extcon device by phandle.

> >

> > extcon_dev(not a reference pointer) is directly added in usb_phy/phy,

> > not via devicetree, how PMIC find it by phandle?

> 

> From my understanding, here we should add one pointer (extcon_dev *),

> since usb phy is not one external connect device.


Agreed.

> 

> >

> >>

> >> >

> >> >> my one concern. (I am afraid if it is enough to send out vbus draw

> >> >> information from USB phy driver, for example you will miss super

> >> >> speed (900mA), which need get the speed information from gadget

> >> >> driver.)

> >> >>

> >> >

> >> > Can we handle this in USB(so has super speed information) and just

> >> > send out 900mA directly?

> >>

> >> From Neil's suggestion, we only have one place to send out current

> >> information from usb phy, so I have this concern and doubt if we

> >> still need the USB charger framework.

> >

> > So if put it in phy/usb_phy, this is a problem, that only one place

> > should have the infor of both speed and usb state, how about put it at

> > usb_gadget, then, e.g. send the notification in

> usb_gadget_vbus_connect()?

> 

> That is same what USB charger did, from this point, we need USB charger to

> send out vbus draw information according to speed and usb state. But I

> should listen to other guys suggestion. Peter and Felipe, what do you think?


So now the only to do work is to find a common place to send the notification out
(based on gadget speed and sate).

Li Jun

> 

> --

> Baolin.wang

> Best Regards

(Exiting) Baolin Wang March 13, 2017, 8:43 a.m. UTC | #11

On 13 March 2017 at 09:09, Jun Li <[e-mail]> wrote:
> Hi,
>
>> -----Original Message-----
>> From: Baolin Wang [mailto:[e-mail]]
>> Sent: Friday, March 10, 2017 6:52 PM
>> To: Jun Li <[e-mail]>
>> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH
>> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry
>> Eremin-Solenikov <[e-mail]>; David Woodhouse
>> <[e-mail]>; [e-mail]; Marek Szyprowski
>> <[e-mail]>; Ruslan Bilovol <[e-mail]>;
>> Peter Chen <[e-mail]>; Alan Stern
>> <[e-mail]>; [e-mail]; Yoshihiro Shimoda
>> <[e-mail]>; Lee Jones <[e-mail]>;
>> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;
>> Charles Keepax <[e-mail]>;
>> [e-mail]; Linux PM list <linux-
>> [e-mail]>; USB <[e-mail]>; device-
>> [e-mail]; LKML <[e-mail]>
>> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with
>> the usb gadget power negotation
>>
>> On 10 March 2017 at 16:27, Jun Li <[e-mail]> wrote:
>> > Hi
>> >
>> >> -----Original Message-----
>> >> From: Baolin Wang [mailto:[e-mail]]
>> >> Sent: Friday, March 10, 2017 3:15 PM
>> >> To: Jun Li <[e-mail]>
>> >> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg
>> >> KH <[e-mail]>; Sebastian Reichel <[e-mail]>;
>> >> Dmitry Eremin-Solenikov <[e-mail]>; David Woodhouse
>> >> <[e-mail]>; [e-mail]; Marek Szyprowski
>> >> <[e-mail]>; Ruslan Bilovol
>> >> <[e-mail]>; Peter Chen <[e-mail]>;
>> >> Alan Stern <[e-mail]>; [e-mail];
>> >> Yoshihiro Shimoda <[e-mail]>; Lee Jones
>> >> <[e-mail]>; Mark Brown <[e-mail]>; John Stultz
>> >> <[e-mail]>; Charles Keepax
>> >> <[e-mail]>;
>> >> [e-mail]; Linux PM list <linux-
>> >> [e-mail]>; USB <[e-mail]>; device-
>> >> [e-mail]; LKML
>> >> <[e-mail]>
>> >> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal
>> >> with the usb gadget power negotation
>> >>
>> >> On 10 March 2017 at 14:30, Jun Li <[e-mail]> wrote:
>> >> >> >> >
>> >> >> >> > Will generic phy need add extcon as well?
>> >> >> >>
>> >> >> >> Yes, will add a 'struct extcon_dev*' in 'struct usb_phy', which
>> >> >> >> will be common code.
>> >> >> >>
>> >> >> >
>> >> >> > I mean the common code need add 'struct extcon_dev' into both
>> >> >> > 'struct phy' and 'struct usb_phy', right? as some/new usb phy
>> >> >> > use that generic phy
>> >> >> driver.
>> >> >>
>> >> >> Ah, you remind me. Seems we need also add one 'struct extcon_dev'
>> >> >> into 'struct phy'.
>> >> >>
>> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >> Secondly, I also agreed with Peter's comments: Not only
>> >> >> >> >> >> USB PHY to register an extcon, but also for the drivers
>> >> >> >> >> >> which can detect USB charger type, it may be USB
>> >> >> >> >> >> controller driver, USB type-c driver, pmic driver, and
>> >> >> >> >> >> these drivers may not have an extcon device since the
>> >> >> >> >> >> internal part can finish
>> >> the vbus detect.
>> >> >> >> >> >
>> >> >> >> >> > Whichever part can detect vbus, the driver for that part
>> >> >> >> >> > must be able to find the extcon and trigger a notification.
>> >> >> >> >> > Maybe one part can detect VBUS, another can measure the
>> >> >> >> >> > resistance on ID and a third can work through the state
>> >> >> >> >> > machine to determine if D+ and D- are shorted together.
>> >> >> >> >> > Somehow these three need to work together to determine
>> >> >> >> >> > what is
>> >> >> >> >> plugged
>> >> >> >> >> > in to the external connection port.  Somewhere there much
>> >> >> >> >> > an
>> >> >> 'extcon'
>> >> >> >> >> > device which represents that port and which the three
>> >> >> >> >> > devices can find and can interact with.
>> >> >> >> >> > I think it makes sense for the usb_phy to be the connection
>> point.
>> >> >> >> >> > Each of the devices can get to the phy, and the phy can
>> >> >> >> >> > get to the
>> >> >> >> extcon.
>> >> >> >> >> > It doesn't matter very much if the usb phy driver creates
>> >> >> >> >> > the extcon, or if something else creates the extcon and
>> >> >> >> >> > the phy driver performs a lookup to find it (e.g. based on
>> devicetree info).
>> >> >> >> >> >
>> >> >> >> >> > The point is that there is obviously an external physical
>> >> >> >> >> > connection, and so there should be an 'extcon' device that
>> >> >> represents it.
>> >> >> >> >>
>> >> >> >> >> Peter & Jun, is it OK for you every phy has one extcon
>> >> >> >> >> device to receive VBUS notification, especially for
>> >> >> >> >> detecting the charger type by
>> >> >> >> software?
>> >> >> >> >>
>> >> >> >> >
>> >> >> >> > My understanding is phy/usb_phy as the connection point, will
>> >> >> >> > send the notification to PMIC driver which actually control
>> >> >> >> > the charge current, also this will be done in your common
>> >> >> >> > framework,
>> >> right?
>> >> >> >>
>> >> >> >> Not in USB charger framework. If we are all agree every usb_phy
>> >> >> >> can register one extcon device, can get correct charger type
>> >> >> >> and send out correct vbus_draw information, then we don't need
>> >> >> >> USB charger framework as Neil suggested. So this will be okay
>> >> >> >> for your case (especially for detecting the charger type by
>> software) ?
>> >> >> >
>> >> >> > In my case, charger detection is done by controller driver and I
>> >> >> > need do charger type detection internally, and only pass the
>> >> >> > current draw info via phy which will send out, this seems ok for
>> >> >> > me, but I think it will be good if you or someone can show us an
>> >> >> > example user based on the
>> >> >> design Neil suggested.
>> >> >> > Will you work out that common code if this USB charger framework
>> >> >> > is not
>> >> >> needed?
>> >> >>
>> >> >> I will add  a 'struct extcon_dev*' in 'struct usb_phy' and struct
>> >> >> phy“. Others are already ready if everyone has no complain about
>> >> >> current design, except
>> >> >
>> >> > Only adding extcon_dev into usb_phy/phy  and all others are ready?
>> >> > My understanding you will also do:
>> >> > - We need find a central place to send the notification(phy common
>> part).
>> >>
>> >> That will include these implementation when adding extcon_dev.
>> >>
>> >
>> > OK, thanks.
>> >
>> >> > - If the extcon_dev is directly added in usb_phy/phy, PMIC needs
>> >> > some
>> >> API to findup it.
>> >>
>> >> PMIC can find extcon device by phandle.
>> >
>> > extcon_dev(not a reference pointer) is directly added in usb_phy/phy,
>> > not via devicetree, how PMIC find it by phandle?
>>
>> From my understanding, here we should add one pointer (extcon_dev *),
>> since usb phy is not one external connect device.
>
> Agreed.
>
>>
>> >
>> >>
>> >> >
>> >> >> my one concern. (I am afraid if it is enough to send out vbus draw
>> >> >> information from USB phy driver, for example you will miss super
>> >> >> speed (900mA), which need get the speed information from gadget
>> >> >> driver.)
>> >> >>
>> >> >
>> >> > Can we handle this in USB(so has super speed information) and just
>> >> > send out 900mA directly?
>> >>
>> >> From Neil's suggestion, we only have one place to send out current
>> >> information from usb phy, so I have this concern and doubt if we
>> >> still need the USB charger framework.
>> >
>> > So if put it in phy/usb_phy, this is a problem, that only one place
>> > should have the infor of both speed and usb state, how about put it at
>> > usb_gadget, then, e.g. send the notification in
>> usb_gadget_vbus_connect()?
>>
>> That is same what USB charger did, from this point, we need USB charger to
>> send out vbus draw information according to speed and usb state. But I
>> should listen to other guys suggestion. Peter and Felipe, what do you think?
>
> So now the only to do work is to find a common place to send the notification out
> (based on gadget speed and sate).

Yes.

Jun Li March 14, 2017, 1:10 a.m. UTC | #12

Hi,

> -----Original Message-----

> From: Baolin Wang [mailto:[e-mail]]

> Sent: Monday, March 13, 2017 4:44 PM

> To: Jun Li <[e-mail]>

> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH

> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry

> Eremin-Solenikov <[e-mail]>; David Woodhouse

> <[e-mail]>; [e-mail]; Marek Szyprowski

> <[e-mail]>; Ruslan Bilovol <[e-mail]>;

> Peter Chen <[e-mail]>; Alan Stern

> <[e-mail]>; [e-mail]; Yoshihiro Shimoda

> <[e-mail]>; Lee Jones <[e-mail]>;

> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;

> Charles Keepax <[e-mail]>;

> [e-mail]; Linux PM list <linux-

> [e-mail]>; USB <[e-mail]>; device-

> [e-mail]; LKML <[e-mail]>

> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with

> the usb gadget power negotation

> 

... ...
> >> That is same what USB charger did, from this point, we need USB

> >> charger to send out vbus draw information according to speed and usb

> >> state. But I should listen to other guys suggestion. Peter and Felipe, what

> do you think?


Instead of waiting for maintainer's comments on this long discussion, I'd suggest
you directly post the patches for the required change, so they can easily know
what's the conclusion/solution looks like.

Li Jun

> >

> > So now the only to do work is to find a common place to send the

> > notification out (based on gadget speed and sate).

> 

> Yes.

> 

> --

> Baolin.wang

> Best Regards

(Exiting) Baolin Wang March 14, 2017, 2:03 a.m. UTC | #13

On 14 March 2017 at 09:10, Jun Li <[e-mail]> wrote:
> Hi,
>
>> -----Original Message-----
>> From: Baolin Wang [mailto:[e-mail]]
>> Sent: Monday, March 13, 2017 4:44 PM
>> To: Jun Li <[e-mail]>
>> Cc: NeilBrown <[e-mail]>; Felipe Balbi <[e-mail]>; Greg KH
>> <[e-mail]>; Sebastian Reichel <[e-mail]>; Dmitry
>> Eremin-Solenikov <[e-mail]>; David Woodhouse
>> <[e-mail]>; [e-mail]; Marek Szyprowski
>> <[e-mail]>; Ruslan Bilovol <[e-mail]>;
>> Peter Chen <[e-mail]>; Alan Stern
>> <[e-mail]>; [e-mail]; Yoshihiro Shimoda
>> <[e-mail]>; Lee Jones <[e-mail]>;
>> Mark Brown <[e-mail]>; John Stultz <[e-mail]>;
>> Charles Keepax <[e-mail]>;
>> [e-mail]; Linux PM list <linux-
>> [e-mail]>; USB <[e-mail]>; device-
>> [e-mail]; LKML <[e-mail]>
>> Subject: Re: [PATCH v19 0/4] Introduce usb charger framework to deal with
>> the usb gadget power negotation
>>
> ... ...
>> >> That is same what USB charger did, from this point, we need USB
>> >> charger to send out vbus draw information according to speed and usb
>> >> state. But I should listen to other guys suggestion. Peter and Felipe, what
>> do you think?
>
> Instead of waiting for maintainer's comments on this long discussion, I'd suggest
> you directly post the patches for the required change, so they can easily know
> what's the conclusion/solution looks like.

That's right, I am creating patches for adding extcon_dev in
phy/usb_phy. Thanks.

NeilBrown March 28, 2017, 11:04 p.m. UTC | #14

On Tue, Mar 07 2017, Baolin Wang wrote:

> On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:
>
>>
>> I understand your reluctance to change drivers that you cannot test.
>> An alternative it do change all the
>>   atomic_notifier_call_chain(.*notifier,
>> calls that don't pass a pointer to vbus_draw to pass NULL, and to
>> declare the passing of NULL to be deprecated (so hopefully people won't
>> use it in new code).
>> Then any notification callback that expects a current can just ignore
>> calls where the pointer is NULL.
>
> I am afraid if it is enough to send out vbus draw information from USB
> phy driver, for example you will miss super speed (900mA), which need
> get the speed information from gadget driver.

When the gadget driver determines that 900mA is available, it calls
usb_phy_set_power() which calls the ->set_power() method on the usb_phy.
The usb_phy the uses the notifier to inform all interested parties
that 900mA is available.

NeilBrown

(Exiting) Baolin Wang March 30, 2017, 3:16 a.m. UTC | #15

Hi,

On 29 March 2017 at 07:04, NeilBrown <[e-mail]> wrote:
> On Tue, Mar 07 2017, Baolin Wang wrote:
>
>> On 3 March 2017 at 10:23, NeilBrown <[e-mail]> wrote:
>>
>>>
>>> I understand your reluctance to change drivers that you cannot test.
>>> An alternative it do change all the
>>>   atomic_notifier_call_chain(.*notifier,
>>> calls that don't pass a pointer to vbus_draw to pass NULL, and to
>>> declare the passing of NULL to be deprecated (so hopefully people won't
>>> use it in new code).
>>> Then any notification callback that expects a current can just ignore
>>> calls where the pointer is NULL.
>>
>> I am afraid if it is enough to send out vbus draw information from USB
>> phy driver, for example you will miss super speed (900mA), which need
>> get the speed information from gadget driver.
>
> When the gadget driver determines that 900mA is available, it calls
> usb_phy_set_power() which calls the ->set_power() method on the usb_phy.
> The usb_phy the uses the notifier to inform all interested parties
> that 900mA is available.

That is one possible way. Now we only set vbus draw by
usb_gadget_vbus_draw() after setting config and suspend/resume usb
device. Maybe we can add one condition in usb_gadget_vbus_draw() like:

if (mA >= 500 && gadet->speed >= SUPER_SPEED)
     mA = 900;

Patch

diff --git a/drivers/usb/gadget/udc/pxa27x_udc.c b/drivers/usb/gadget/udc/pxa27x_udc.c
index e1335ad5bce9..885a6c80fd08 100644
--- a/drivers/usb/gadget/udc/pxa27x_udc.c
+++ b/drivers/usb/gadget/udc/pxa27x_udc.c
@@ -1669,7 +1669,8 @@  static int pxa_udc_vbus_draw(struct usb_gadget *_gadget, unsigned mA)
 static int pxa_udc_phy_event(struct notifier_block *nb, unsigned long action,
 			     void *data)
 {
-	struct usb_gadget *gadget = data;
+	struct pxa_udc *udc = container_of(nb, struct pxa_udc, nb);
+	struct usb_gadget *gadget = &udc->gadget;
 
 	switch (action) {
 	case USB_EVENT_VBUS:
@@ -1683,10 +1684,6 @@  static int pxa_udc_phy_event(struct notifier_block *nb, unsigned long action,
 	}
 }
 
-static struct notifier_block pxa27x_udc_phy = {
-	.notifier_call = pxa_udc_phy_event,
-};
-
 static int pxa27x_udc_start(struct usb_gadget *g,
 		struct usb_gadget_driver *driver);
 static int pxa27x_udc_stop(struct usb_gadget *g);
@@ -2504,8 +2501,9 @@  static int pxa_udc_probe(struct platform_device *pdev)
 		goto err;
 	}
 
+	udc->nb.notifier_call = pxa_udc_phy_event;
 	if (!IS_ERR_OR_NULL(udc->transceiver))
-		usb_register_notifier(udc->transceiver, &pxa27x_udc_phy);
+		usb_register_notifier(udc->transceiver, &udc->nb);
 	retval = usb_add_gadget_udc(&pdev->dev, &udc->gadget);
 	if (retval)
 		goto err_add_gadget;
@@ -2517,7 +2515,7 @@  static int pxa_udc_probe(struct platform_device *pdev)
 
 err_add_gadget:
 	if (!IS_ERR_OR_NULL(udc->transceiver))
-		usb_unregister_notifier(udc->transceiver, &pxa27x_udc_phy);
+		usb_unregister_notifier(udc->transceiver, &udc->nb);
 err:
 	clk_unprepare(udc->clk);
 	return retval;
@@ -2535,7 +2533,7 @@  static int pxa_udc_remove(struct platform_device *_dev)
 	pxa_cleanup_debugfs(udc);
 
 	if (!IS_ERR_OR_NULL(udc->transceiver))
-		usb_unregister_notifier(udc->transceiver, &pxa27x_udc_phy);
+		usb_unregister_notifier(udc->transceiver, &udc->nb);
 	usb_put_phy(udc->transceiver);
 
 	udc->transceiver = NULL;
diff --git a/drivers/usb/gadget/udc/pxa27x_udc.h b/drivers/usb/gadget/udc/pxa27x_udc.h
index cea2cb79b30c..acefb07427bd 100644
--- a/drivers/usb/gadget/udc/pxa27x_udc.h
+++ b/drivers/usb/gadget/udc/pxa27x_udc.h
@@ -461,6 +461,8 @@  struct pxa_udc {
 	struct gpio_desc			*gpiod;
 	struct usb_phy				*transceiver;
 
+	struct notifier_block			nb;
+
 	enum ep0_state				ep0state;
 	struct udc_stats			stats;