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Commit 75996055 authored by chenchangcheng's avatar chenchangcheng Committed by Greg Kroah-Hartman
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media: uvcvideo: Fix bandwidth issue for Alcor camera 



[ Upstream commit 9764401bf6f8a20eb11c2e78470f20fee91a9ea7 ]

Some broken device return wrong dwMaxPayloadTransferSize fields as
follows:

[  218.632537] uvcvideo: Device requested 2752512 B/frame bandwidth.
[  218.632598] uvcvideo: No fast enough alt setting for requested bandwidth.

When dwMaxPayloadTransferSize is greater than maxpsize, it will prevent
the camera from starting. So use the bandwidth of maxpsize.

Signed-off-by: default avatarchenchangcheng <chenchangcheng@kylinos.cn>
Reviewed-by: default avatarRicardo Ribalda <ribalda@chromium.org>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20250510061803.811433-1-ccc194101@163.com


Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: default avatarHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 7a41ecfc

drivers/media/usb/uvc/uvc_video.c

+9 −0
Original line number Diff line number Diff line
@@ -228,6 +228,15 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream, 


		ctrl->dwMaxPayloadTransferSize = bandwidth;

	}



	if (stream->intf->num_altsetting > 1 &&

	    ctrl->dwMaxPayloadTransferSize > stream->maxpsize) {

		dev_warn_ratelimited(&stream->intf->dev,

				     "UVC non compliance: the max payload transmission size (%u) exceeds the size of the ep max packet (%u). Using the max size.\n",

				     ctrl->dwMaxPayloadTransferSize,

				     stream->maxpsize);

		ctrl->dwMaxPayloadTransferSize = stream->maxpsize;

	}

}



static size_t uvc_video_ctrl_size(struct uvc_streaming *stream)