[v2] usb: gadget: uvc: add bInterval checking for HS mode

Message ID 20210308125338.4824-1-pawell@gli-login.cadence.com
State New
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Series
  • [v2] usb: gadget: uvc: add bInterval checking for HS mode
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Commit Message

Pawel Laszczak March 8, 2021, 12:53 p.m.
From: Pawel Laszczak <pawell@cadence.com>

Patch adds extra checking for bInterval passed by configfs.
The 5.6.4 chapter of USB Specification (rev. 2.0) say:
"A high-bandwidth endpoint must specify a period of 1x125 µs
(i.e., a bInterval value of 1)."

The issue was observed during testing UVC class on CV.
I treat this change as improvement because we can control
bInterval by configfs.

Signed-off-by: Pawel Laszczak <pawell@cadence.com>

---
Changlog:
v2:
- removed duplicated assignment

 drivers/usb/gadget/function/f_uvc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Peter Chen March 14, 2021, 2:29 a.m. | #1
On 21-03-08 13:53:38, Pawel Laszczak wrote:
> From: Pawel Laszczak <pawell@cadence.com>

> 

> Patch adds extra checking for bInterval passed by configfs.

> The 5.6.4 chapter of USB Specification (rev. 2.0) say:

> "A high-bandwidth endpoint must specify a period of 1x125 µs

> (i.e., a bInterval value of 1)."

> 

> The issue was observed during testing UVC class on CV.

> I treat this change as improvement because we can control

> bInterval by configfs.

> 

> Signed-off-by: Pawel Laszczak <pawell@cadence.com>

> 

> ---

> Changlog:

> v2:

> - removed duplicated assignment

> 

>  drivers/usb/gadget/function/f_uvc.c | 7 ++++++-

>  1 file changed, 6 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c

> index 44b4352a2676..ed77a126a74f 100644

> --- a/drivers/usb/gadget/function/f_uvc.c

> +++ b/drivers/usb/gadget/function/f_uvc.c

> @@ -633,7 +633,12 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)

>  

>  	uvc_hs_streaming_ep.wMaxPacketSize =

>  		cpu_to_le16(max_packet_size | ((max_packet_mult - 1) << 11));

> -	uvc_hs_streaming_ep.bInterval = opts->streaming_interval;

> +

> +	/* A high-bandwidth endpoint must specify a bInterval value of 1 */

> +	if (max_packet_mult > 1)

> +		uvc_hs_streaming_ep.bInterval = 1;

> +	else

> +		uvc_hs_streaming_ep.bInterval = opts->streaming_interval;

>  

>  	uvc_ss_streaming_ep.wMaxPacketSize = cpu_to_le16(max_packet_size);

>  	uvc_ss_streaming_ep.bInterval = opts->streaming_interval;

> -- 

> 2.25.1

> 


Reviewed-by: Peter Chen <peter.chen@kernel.org>


-- 

Thanks,
Peter Chen
Laurent Pinchart March 14, 2021, 2:40 a.m. | #2
Hi Pawel,

Thank you for the patch.

On Mon, Mar 08, 2021 at 01:53:38PM +0100, Pawel Laszczak wrote:
> From: Pawel Laszczak <pawell@cadence.com>

> 

> Patch adds extra checking for bInterval passed by configfs.

> The 5.6.4 chapter of USB Specification (rev. 2.0) say:

> "A high-bandwidth endpoint must specify a period of 1x125 µs

> (i.e., a bInterval value of 1)."

> 

> The issue was observed during testing UVC class on CV.

> I treat this change as improvement because we can control

> bInterval by configfs.

> 

> Signed-off-by: Pawel Laszczak <pawell@cadence.com>


Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>


Felipe, could you take this patch in your tree ?

> ---

> Changlog:

> v2:

> - removed duplicated assignment

> 

>  drivers/usb/gadget/function/f_uvc.c | 7 ++++++-

>  1 file changed, 6 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c

> index 44b4352a2676..ed77a126a74f 100644

> --- a/drivers/usb/gadget/function/f_uvc.c

> +++ b/drivers/usb/gadget/function/f_uvc.c

> @@ -633,7 +633,12 @@ uvc_function_bind(struct usb_configuration *c, struct usb_function *f)

>  

>  	uvc_hs_streaming_ep.wMaxPacketSize =

>  		cpu_to_le16(max_packet_size | ((max_packet_mult - 1) << 11));

> -	uvc_hs_streaming_ep.bInterval = opts->streaming_interval;

> +

> +	/* A high-bandwidth endpoint must specify a bInterval value of 1 */

> +	if (max_packet_mult > 1)

> +		uvc_hs_streaming_ep.bInterval = 1;

> +	else

> +		uvc_hs_streaming_ep.bInterval = opts->streaming_interval;

>  

>  	uvc_ss_streaming_ep.wMaxPacketSize = cpu_to_le16(max_packet_size);

>  	uvc_ss_streaming_ep.bInterval = opts->streaming_interval;


-- 
Regards,

Laurent Pinchart

Patch

diff --git a/drivers/usb/gadget/function/f_uvc.c b/drivers/usb/gadget/function/f_uvc.c
index 44b4352a2676..ed77a126a74f 100644
--- a/drivers/usb/gadget/function/f_uvc.c
+++ b/drivers/usb/gadget/function/f_uvc.c
@@ -633,7 +633,12 @@  uvc_function_bind(struct usb_configuration *c, struct usb_function *f)
 
 	uvc_hs_streaming_ep.wMaxPacketSize =
 		cpu_to_le16(max_packet_size | ((max_packet_mult - 1) << 11));
-	uvc_hs_streaming_ep.bInterval = opts->streaming_interval;
+
+	/* A high-bandwidth endpoint must specify a bInterval value of 1 */
+	if (max_packet_mult > 1)
+		uvc_hs_streaming_ep.bInterval = 1;
+	else
+		uvc_hs_streaming_ep.bInterval = opts->streaming_interval;
 
 	uvc_ss_streaming_ep.wMaxPacketSize = cpu_to_le16(max_packet_size);
 	uvc_ss_streaming_ep.bInterval = opts->streaming_interval;