From 9bb7262de9c077ccccb129f47d128edb7af5f92e Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Sun, 3 Oct 2010 17:40:29 -0300 Subject: [PATCH] [media] uvcvideo: Set bandwidth to at least 1024 with the FIX_BANDWIDTH quirk The bandwidth estimate computed with the FIX_BANDIWDTH quirk is too low for many cameras. Don't use maximum packet sizes lower than 1024 bytes to try and work around the problem. According to measurements done on two different camera models, the value is high enough to get most resolutions working while not preventing two simultaneous VGA streams at 15 fps. Signed-off-by: Laurent Pinchart Signed-off-by: Mauro Carvalho Chehab --- drivers/media/video/uvc/uvc_video.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/media/video/uvc/uvc_video.c b/drivers/media/video/uvc/uvc_video.c index ee5e2338b417..5a2022c01528 100644 --- a/drivers/media/video/uvc/uvc_video.c +++ b/drivers/media/video/uvc/uvc_video.c @@ -138,6 +138,15 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream, bandwidth /= 8; bandwidth += 12; + /* The bandwidth estimate is too low for many cameras. Don't use + * maximum packet sizes lower than 1024 bytes to try and work + * around the problem. According to measurements done on two + * different camera models, the value is high enough to get most + * resolutions working while not preventing two simultaneous + * VGA streams at 15 fps. + */ + bandwidth = max_t(u32, bandwidth, 1024); + ctrl->dwMaxPayloadTransferSize = bandwidth; } } -- 2.20.1