>
>On Fri, Mar 5, 2021 at 12:40 AM Pawel Laszczak <mailto:paw...@cadence.com>
>wrote:
>From: Pawel Laszczak <mailto:paw...@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 <mailto:paw...@cadence.com>
>---
> drivers/usb/gadget/function/f_uvc.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/drivers/usb/gadget/function/f_uvc.c
>b/drivers/usb/gadget/function/f_uvc.c
>index 44b4352a2676..5d62720bb9e1 100644
>--- a/drivers/usb/gadget/function/f_uvc.c
>+++ b/drivers/usb/gadget/function/f_uvc.c
>@@ -631,6 +631,12 @@ uvc_function_bind(struct usb_configuration *c, struct
>usb_function *f)
> cpu_to_le16(min(opts->streaming_maxpacket, 1023U));
> uvc_fs_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;
>+
>
>There is a "uvc_hs_streaming_ep.bInterval = opts->streaming_interval;" again
>at below code
>Besides, the default value is 1 for opts->streaming_interval. What the real
>issue you observed
>at CV test?
>
The issue occurs when I intentionally set:
echo 3072 > functions/$FUNCTION/streaming_maxpacket
echo 4 > functions/$FUNCTION/streaming_interval
Then for CV CH9 TD 9.5: Endpoint Descriptor test it got:
"(Mult = 2)Illegal high speed isochronous endpoint MaxPacketSize : 0x400
(USB: 1.2.78) A High speed Interrupt/Isochronous endpoint must have a
MaxPacketSize between
683 and 1024 and bInterval value of 1 when the Mult value is two."
For default value CV passed. Of course, I can fix it by changing
streaming_interval, but I thought that
it could be good to have protection against this issue.
Especially since Usb 2 specification say that bInterval must be 1 for high
bandwidth endpoints.
Pawel
>Peter
>
> uvc_hs_streaming_ep.wMaxPacketSize =
> cpu_to_le16(max_packet_size | ((max_packet_mult - 1) << 11));
> uvc_hs_streaming_ep.bInterval = opts->streaming_interval;
>--
>2.25.1
