usb: devio: update max count of DPs per interval for ISOC
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Message ID 1545992864-9530-1-git-send-email-chunfeng.yun@mediatek.com
State New
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  • usb: devio: update max count of DPs per interval for ISOC
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Commit Message

Chunfeng Yun Dec. 28, 2018, 10:27 a.m. UTC
The host shall be able to accept and send up to 96 DPs for
devices operating at Gen 2 speed.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
---
 drivers/usb/core/devio.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

Comments

Greg KH Dec. 28, 2018, 10:51 a.m. UTC | #1
On Fri, Dec 28, 2018 at 06:27:44PM +0800, Chunfeng Yun wrote:
> The host shall be able to accept and send up to 96 DPs for
> devices operating at Gen 2 speed.

Why?  What is this keeping from working properly today?

I need a much better changelog text here in order to be able to accept
this patch.

> 
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> ---
>  drivers/usb/core/devio.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> index a75bc0b8a50f..82c16210e34c 100644
> --- a/drivers/usb/core/devio.c
> +++ b/drivers/usb/core/devio.c
> @@ -1564,12 +1564,10 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
>  		}
>  		for (totlen = u = 0; u < number_of_packets; u++) {
>  			/*
> -			 * arbitrary limit need for USB 3.0
> -			 * bMaxBurst (0~15 allowed, 1~16 packets)
> -			 * bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
> -			 * sizemax: 1024 * 16 * 3 = 49152
> +			 * arbitrary limit need for USB 3.1 Gen2
> +			 * sizemax: 96 DPs at SSP, 96 * 1024 = 98304
>  			 */
> -			if (isopkt[u].length > 49152) {
> +			if (isopkt[u].length > 98304) {

Are we going to have to keep bumping this up as speeds get faster and
faster?

thanks,

greg k-h
Chunfeng Yun Dec. 29, 2018, 2:48 a.m. UTC | #2
Hi,
On Fri, 2018-12-28 at 11:51 +0100, Greg Kroah-Hartman wrote:
> On Fri, Dec 28, 2018 at 06:27:44PM +0800, Chunfeng Yun wrote:
> > The host shall be able to accept and send up to 96 DPs for
> > devices operating at Gen 2 speed.
> 
> Why?  What is this keeping from working properly today?

The failure happened when I tried to send up to 96DPs per an interval
for SSP ISOC transations by libusb, this is used to verify SSP ISOC
function of USB3 GEN2 controller. Maybe for normal scenarios they
needn't transfer greater than 48 DPs in an ISOC interval.
(refer usb3.1r1.0 section 8.12.6 Isochronous Transactions)
> 
> I need a much better changelog text here in order to be able to accept
> this patch.
I'll make the change in next version
> 
> > 
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> > ---
> >  drivers/usb/core/devio.c | 8 +++-----
> >  1 file changed, 3 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> > index a75bc0b8a50f..82c16210e34c 100644
> > --- a/drivers/usb/core/devio.c
> > +++ b/drivers/usb/core/devio.c
> > @@ -1564,12 +1564,10 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
> >  		}
> >  		for (totlen = u = 0; u < number_of_packets; u++) {
> >  			/*
> > -			 * arbitrary limit need for USB 3.0
> > -			 * bMaxBurst (0~15 allowed, 1~16 packets)
> > -			 * bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
> > -			 * sizemax: 1024 * 16 * 3 = 49152
> > +			 * arbitrary limit need for USB 3.1 Gen2
> > +			 * sizemax: 96 DPs at SSP, 96 * 1024 = 98304
> >  			 */
> > -			if (isopkt[u].length > 49152) {
> > +			if (isopkt[u].length > 98304) {
> 
> Are we going to have to keep bumping this up as speeds get faster and
> faster?
Or remove the check of data length? I'm not sure which way is better

> 
> thanks,
> 
> greg k-h
Greg KH Dec. 29, 2018, 12:49 p.m. UTC | #3
On Sat, Dec 29, 2018 at 10:48:40AM +0800, Chunfeng Yun wrote:
> Hi,
> On Fri, 2018-12-28 at 11:51 +0100, Greg Kroah-Hartman wrote:
> > On Fri, Dec 28, 2018 at 06:27:44PM +0800, Chunfeng Yun wrote:
> > > The host shall be able to accept and send up to 96 DPs for
> > > devices operating at Gen 2 speed.
> > 
> > Why?  What is this keeping from working properly today?
> 
> The failure happened when I tried to send up to 96DPs per an interval
> for SSP ISOC transations by libusb, this is used to verify SSP ISOC
> function of USB3 GEN2 controller. Maybe for normal scenarios they
> needn't transfer greater than 48 DPs in an ISOC interval.
> (refer usb3.1r1.0 section 8.12.6 Isochronous Transactions)

Ok, please add this information in the changelog text please.

> > 
> > I need a much better changelog text here in order to be able to accept
> > this patch.
> I'll make the change in next version
> > 
> > > 
> > > Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> > > ---
> > >  drivers/usb/core/devio.c | 8 +++-----
> > >  1 file changed, 3 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
> > > index a75bc0b8a50f..82c16210e34c 100644
> > > --- a/drivers/usb/core/devio.c
> > > +++ b/drivers/usb/core/devio.c
> > > @@ -1564,12 +1564,10 @@ static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
> > >  		}
> > >  		for (totlen = u = 0; u < number_of_packets; u++) {
> > >  			/*
> > > -			 * arbitrary limit need for USB 3.0
> > > -			 * bMaxBurst (0~15 allowed, 1~16 packets)
> > > -			 * bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
> > > -			 * sizemax: 1024 * 16 * 3 = 49152
> > > +			 * arbitrary limit need for USB 3.1 Gen2
> > > +			 * sizemax: 96 DPs at SSP, 96 * 1024 = 98304
> > >  			 */
> > > -			if (isopkt[u].length > 49152) {
> > > +			if (isopkt[u].length > 98304) {
> > 
> > Are we going to have to keep bumping this up as speeds get faster and
> > faster?
> Or remove the check of data length? I'm not sure which way is better

No, we added that check for a good reason, please see the git log for
the details :)

thanks,

greg k-h

Patch
diff mbox series

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index a75bc0b8a50f..82c16210e34c 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -1564,12 +1564,10 @@  static int proc_do_submiturb(struct usb_dev_state *ps, struct usbdevfs_urb *uurb
 		}
 		for (totlen = u = 0; u < number_of_packets; u++) {
 			/*
-			 * arbitrary limit need for USB 3.0
-			 * bMaxBurst (0~15 allowed, 1~16 packets)
-			 * bmAttributes (bit 1:0, mult 0~2, 1~3 packets)
-			 * sizemax: 1024 * 16 * 3 = 49152
+			 * arbitrary limit need for USB 3.1 Gen2
+			 * sizemax: 96 DPs at SSP, 96 * 1024 = 98304
 			 */
-			if (isopkt[u].length > 49152) {
+			if (isopkt[u].length > 98304) {
 				ret = -EINVAL;
 				goto error;
 			}