diff mbox series

[2/2] staging: vchiq: Add details to $CONFIG_VCHIQ_CDEV help text

Message ID 9c9c128b41e31d6bebe646e052aa05c44b19eb83.1627495116.git.ojaswin98@gmail.com (mailing list archive)
State New, archived
Headers show
Series staging: vchiq: Minor fixups to CONFIG_VCHIQ_CDEV | expand

Commit Message

Ojaswin Mujoo July 28, 2021, 6:37 p.m. UTC
Add some details to the Kconfig definition of $CONFIG_VCHIQ_CDEV to help
make the motive behind it a bit more clear.

Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com>
---
 drivers/staging/vc04_services/Kconfig | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Comments

Greg KH July 28, 2021, 6:46 p.m. UTC | #1
On Thu, Jul 29, 2021 at 12:07:17AM +0530, Ojaswin Mujoo wrote:
> Add some details to the Kconfig definition of $CONFIG_VCHIQ_CDEV to help
> make the motive behind it a bit more clear.
> 
> Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com>
> ---
>  drivers/staging/vc04_services/Kconfig | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig
> index 2b70c37cdd09..cb02d8a4cb74 100644
> --- a/drivers/staging/vc04_services/Kconfig
> +++ b/drivers/staging/vc04_services/Kconfig
> @@ -25,8 +25,12 @@ config VCHIQ_CDEV
>  	bool "VCHIQ Character Driver"
>  	default y
>  	help
> -		Enable the creation of VCHIQ character driver to help
> -		communicate with the Videocore platform.
> +		Enable the creation of VCHIQ character driver to help communicate
> +		with the VideoCore platform. The cdev exposes ioctls used by
> +		userspace libraries and testing tools to interact with VideoCore.
> +		This can be set to 'N' if the VideoCore communication is not needed
> +		by userspace but only by other kernel modules (like bcm2835-audio).
> +		If not sure, set this to 'Y'.

I still do not understand if I need this driver or not, and I have this
hardware!  What functionality does this driver accomplish?  What is
VideoCore?

thanks,

greg k-h
Ojaswin Mujoo July 28, 2021, 8 p.m. UTC | #2
On Wed, Jul 28, 2021 at 08:46:51PM +0200, Greg KH wrote:
> On Thu, Jul 29, 2021 at 12:07:17AM +0530, Ojaswin Mujoo wrote:
> > Add some details to the Kconfig definition of $CONFIG_VCHIQ_CDEV to help
> > make the motive behind it a bit more clear.
> > 
> > Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com>
> > ---
> >  drivers/staging/vc04_services/Kconfig | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig
> > index 2b70c37cdd09..cb02d8a4cb74 100644
> > --- a/drivers/staging/vc04_services/Kconfig
> > +++ b/drivers/staging/vc04_services/Kconfig
> > @@ -25,8 +25,12 @@ config VCHIQ_CDEV
> >  	bool "VCHIQ Character Driver"
> >  	default y
> >  	help
> > -		Enable the creation of VCHIQ character driver to help
> > -		communicate with the Videocore platform.
> > +		Enable the creation of VCHIQ character driver to help communicate
> > +		with the VideoCore platform. The cdev exposes ioctls used by
> > +		userspace libraries and testing tools to interact with VideoCore.
> > +		This can be set to 'N' if the VideoCore communication is not needed
> > +		by userspace but only by other kernel modules (like bcm2835-audio).
> > +		If not sure, set this to 'Y'.
> 
> I still do not understand if I need this driver or not, and I have this
> hardware!  What functionality does this driver accomplish?  What is
> VideoCore?
Hey Greg,

I believe I can add this under the CONFIG_BCM2835_VCHIQ config option,
as that enables the core driver that implements the functions to
communicate with VideoCore platform? 

This config option merely adds a cdev which exposes the the core
driver's functionality to userspace. 

Regards,
Ojaswin
> 
> thanks,
> 
> greg k-h
Stefan Wahren July 28, 2021, 8:39 p.m. UTC | #3
Am 28.07.21 um 22:00 schrieb Ojaswin Mujoo:
> On Wed, Jul 28, 2021 at 08:46:51PM +0200, Greg KH wrote:
>> On Thu, Jul 29, 2021 at 12:07:17AM +0530, Ojaswin Mujoo wrote:
>>> Add some details to the Kconfig definition of $CONFIG_VCHIQ_CDEV to help
>>> make the motive behind it a bit more clear.
>>>
>>> Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com>
>>> ---
>>>  drivers/staging/vc04_services/Kconfig | 8 ++++++--
>>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig
>>> index 2b70c37cdd09..cb02d8a4cb74 100644
>>> --- a/drivers/staging/vc04_services/Kconfig
>>> +++ b/drivers/staging/vc04_services/Kconfig
>>> @@ -25,8 +25,12 @@ config VCHIQ_CDEV
>>>  	bool "VCHIQ Character Driver"
>>>  	default y
>>>  	help
>>> -		Enable the creation of VCHIQ character driver to help
>>> -		communicate with the Videocore platform.
>>> +		Enable the creation of VCHIQ character driver to help communicate
>>> +		with the VideoCore platform. The cdev exposes ioctls used by
>>> +		userspace libraries and testing tools to interact with VideoCore.
>>> +		This can be set to 'N' if the VideoCore communication is not needed
>>> +		by userspace but only by other kernel modules (like bcm2835-audio).
>>> +		If not sure, set this to 'Y'.
>> I still do not understand if I need this driver or not, and I have this
>> hardware!  What functionality does this driver accomplish?  What is
>> VideoCore?
> Hey Greg,
>
> I believe I can add this under the CONFIG_BCM2835_VCHIQ config option,
> as that enables the core driver that implements the functions to
> communicate with VideoCore platform? 

Sorry, today i'm too tired to give a good explanation. VideoCore is the
VPU inside the BCM283x SoC. It runs a firmware and VCHIQ provides a way
to communicate with this firmware / VPU. The VCHIQ driver is required to
get access to the audio jack and camera interface (see depending drivers).

Unfortunately i don't have an application list by the hand which uses
the CDEV interface for VCHIQ, please use this link [1] as a starting point.

[1] - https://github.com/raspberrypi/userland

>
> This config option merely adds a cdev which exposes the the core
> driver's functionality to userspace. 
>
> Regards,
> Ojaswin
>> thanks,
>>
>> greg k-h
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Ojaswin Mujoo July 29, 2021, 1:47 p.m. UTC | #4
On Wed, Jul 28, 2021 at 10:39:38PM +0200, Stefan Wahren wrote:
> Am 28.07.21 um 22:00 schrieb Ojaswin Mujoo:
> > On Wed, Jul 28, 2021 at 08:46:51PM +0200, Greg KH wrote:
> >> On Thu, Jul 29, 2021 at 12:07:17AM +0530, Ojaswin Mujoo wrote:
> >>> Add some details to the Kconfig definition of $CONFIG_VCHIQ_CDEV to help
> >>> make the motive behind it a bit more clear.
> >>>
> >>> Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com>
> >>> ---
> >>>  drivers/staging/vc04_services/Kconfig | 8 ++++++--
> >>>  1 file changed, 6 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig
> >>> index 2b70c37cdd09..cb02d8a4cb74 100644
> >>> --- a/drivers/staging/vc04_services/Kconfig
> >>> +++ b/drivers/staging/vc04_services/Kconfig
> >>> @@ -25,8 +25,12 @@ config VCHIQ_CDEV
> >>>  	bool "VCHIQ Character Driver"
> >>>  	default y
> >>>  	help
> >>> -		Enable the creation of VCHIQ character driver to help
> >>> -		communicate with the Videocore platform.
> >>> +		Enable the creation of VCHIQ character driver to help communicate
> >>> +		with the VideoCore platform. The cdev exposes ioctls used by
> >>> +		userspace libraries and testing tools to interact with VideoCore.
> >>> +		This can be set to 'N' if the VideoCore communication is not needed
> >>> +		by userspace but only by other kernel modules (like bcm2835-audio).
> >>> +		If not sure, set this to 'Y'.
> >> I still do not understand if I need this driver or not, and I have this
> >> hardware!  What functionality does this driver accomplish?  What is
> >> VideoCore?
> > Hey Greg,
> >
> > I believe I can add this under the CONFIG_BCM2835_VCHIQ config option,
> > as that enables the core driver that implements the functions to
> > communicate with VideoCore platform? 
> 
> Sorry, today i'm too tired to give a good explanation. VideoCore is the
> VPU inside the BCM283x SoC. It runs a firmware and VCHIQ provides a way
> to communicate with this firmware / VPU. The VCHIQ driver is required to
> get access to the audio jack and camera interface (see depending drivers).
> 
> Unfortunately i don't have an application list by the hand which uses
> the CDEV interface for VCHIQ, please use this link [1] as a starting point.
> 
> [1] - https://github.com/raspberrypi/userland
> 
Hi Stefan

Thanks for the brief, its good enough to help me get started. I've also
been looking more closely into this driver in my free time lately and I
can try to come up with a small summary to use as the help text. I'll
add it in v2 of this patch.

Regards,
Ojaswin
> >
> > This config option merely adds a cdev which exposes the the core
> > driver's functionality to userspace. 
> >
> > Regards,
> > Ojaswin
> >> thanks,
> >>
> >> greg k-h
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
diff mbox series

Patch

diff --git a/drivers/staging/vc04_services/Kconfig b/drivers/staging/vc04_services/Kconfig
index 2b70c37cdd09..cb02d8a4cb74 100644
--- a/drivers/staging/vc04_services/Kconfig
+++ b/drivers/staging/vc04_services/Kconfig
@@ -25,8 +25,12 @@  config VCHIQ_CDEV
 	bool "VCHIQ Character Driver"
 	default y
 	help
-		Enable the creation of VCHIQ character driver to help
-		communicate with the Videocore platform.
+		Enable the creation of VCHIQ character driver to help communicate
+		with the VideoCore platform. The cdev exposes ioctls used by
+		userspace libraries and testing tools to interact with VideoCore.
+		This can be set to 'N' if the VideoCore communication is not needed
+		by userspace but only by other kernel modules (like bcm2835-audio).
+		If not sure, set this to 'Y'.
 
 endif