From 55dc87dc2ac18e33ba2fbe74861f7af68cfdd62d Mon Sep 17 00:00:00 2001 From: chenchangcheng Date: Sat, 10 May 2025 14:18:03 +0800 Subject: [PATCH] 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: chenchangcheng Reviewed-by: Ricardo Ribalda Reviewed-by: Laurent Pinchart Link: https://lore.kernel.org/r/20250510061803.811433-1-ccc194101@163.com Signed-off-by: Laurent Pinchart Signed-off-by: Hans Verkuil Signed-off-by: Sasha Levin --- drivers/media/usb/uvc/uvc_video.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index eab7b8f557305..17ec298ee4f7d 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -258,6 +258,15 @@ 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) -- 2.47.3