Re: [PATCH] uvc-gadget: Fix Set Interface (alternate setting) response behaviour

From: Felipe Balbi
Date: Tue Mar 07 2017 - 06:04:48 EST



Hi,

Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> writes:
> Hi Roger,
>
> Thank you for the patch.
>
> On Friday 03 Mar 2017 13:17:15 Roger Quadros wrote:
>> On alternate setting change, webcam gadget sends us a UVC_EVENT_STREAMON
>> or UVC_EVENT_STREAMOFF event. It expects delayed status response on
>> STREAMON event only but doesn't expect us to send that response over USB.
>> It sends the delayed response when we issue the VIDIOC_STREAMON ioctl.
>>
>> So we must not send UVCIOC_SEND_RESPONSE ioctl in these cases that too
>> with invalid response length.
>
> The commit message only explains why we should not call UVCIOC_SEND_RESPONSE
> in response to a STREAMON event, but not why we shouldn't either in response
> to a STREAMOFF event. The patch is correct changing both, but I propose
> wording the above two paragraphs as follows.
>
> "uvc-gadget: Do not send Set Interface (alternate setting) response twice
>
> On alternate setting change, the webcam gadget sends us a UVC_EVENT_STREAMON
> or UVC_EVENT_STREAMOFF event. In the first case, the driver will issue a
> delayed status response automatically when we call the VIDIOC_STREAMON ioctl.
> In the second case, the driver sends the status response immediately. We must
> thus not send the status response manually with UVCIOC_SEND_RESPONSE in any of
> those cases."
>
> If you're fine with that I'll change the message when applying, there's no
> need to resend the patch.

I have this in my testing/fixes and was planning to send it to Greg this
week. I can drop it from my queue, no problem, but then let me know as
you would need my acked-by.

--
balbi

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