| Message ID | 20240114213518.03e22698@foxbook (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: uvcvideo: extend the bandwdith quirk to USB 3.x | expand |
Hi Michal Thanks for your patch. Out of curiosity, what camera are you using? Could you also share the patch with the quirk? Thanks! On Sun, 14 Jan 2024 at 21:35, Michal Pecio <michal.pecio@gmail.com> wrote: > > The bandwidth fixup quirk which is needed to run certain buggy cameras > doesn't know that SuperSpeed exists and has the same 8 service intervals > per millisecond as High Speed; hence its calculations are badly wrong. > > Assume that all speeds from HS up use 8 intervals per millisecond. > > No further changes are required. Updated code has been confirmed to work > properly with a SuperSpeed camera, as well as some High Speed ones. > > Signed-off-by: Michal Pecio <michal.pecio@gmail.com> Reviewed-by: Ricardo Ribalda <ribalda@chromium.org> > --- > drivers/media/usb/uvc/uvc_video.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c > index 28dde08ec6c5..4b86bef06a52 100644 > --- a/drivers/media/usb/uvc/uvc_video.c > +++ b/drivers/media/usb/uvc/uvc_video.c > @@ -214,13 +214,13 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream, > * Compute a bandwidth estimation by multiplying the frame > * size by the number of video frames per second, divide the > * result by the number of USB frames (or micro-frames for > - * high-speed devices) per second and add the UVC header size > - * (assumed to be 12 bytes long). > + * high- and super-speed devices) per second and add the UVC > + * header size (assumed to be 12 bytes long). > */ > bandwidth = frame->wWidth * frame->wHeight / 8 * format->bpp; > bandwidth *= 10000000 / interval + 1; > bandwidth /= 1000; > - if (stream->dev->udev->speed == USB_SPEED_HIGH) > + if (stream->dev->udev->speed >= USB_SPEED_HIGH) > bandwidth /= 8; > bandwidth += 12; > > -- > 2.43.0 > >
Hi, > Out of curiosity, what camera are you using? Could you also share the > patch with the quirk? I have no idea what camera I am using ;) It's some dodgy no-name thing which doesn't even have "made in China" written on it and reports IDs belonging to a completely different kind of camera. But it sort of works, so what the heck. And I use the BW quirk with it because it otherwise asks for way too much. Squatting on others' IDs appears to be a fancy new cost reduction trick (not the first time I see it happen). I'm not really convinced that it would be a good idea to push quirks on such IDs upstream, but I figured the BW calculation fix could be useful. Regards, Michal
Hi again, > > Out of curiosity, what camera are you using? Could you also share > > the patch with the quirk? > > I have no idea what camera I am using ;) > > It's some dodgy no-name thing which doesn't even have "made in China" > written on it and reports IDs belonging to a completely different kind > of camera. In a plot twist, I discovered that the original camera has already had this quirk applied 15 years ago. So my ID squatter gets the quirk too. (I think it's a squatter, the old chip was USB 2.0 and this is USB 3.0). Not sure why I believed otherwise and used to set it with modprobe. Maybe I noticed the excessive bandwdith requests made by buggy quirk, then force-enabled the quirk hoping it will solve them, then fixed the quirk to actually get it right. Michal
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c index 28dde08ec6c5..4b86bef06a52 100644 --- a/drivers/media/usb/uvc/uvc_video.c +++ b/drivers/media/usb/uvc/uvc_video.c @@ -214,13 +214,13 @@ static void uvc_fixup_video_ctrl(struct uvc_streaming *stream, * Compute a bandwidth estimation by multiplying the frame * size by the number of video frames per second, divide the * result by the number of USB frames (or micro-frames for - * high-speed devices) per second and add the UVC header size - * (assumed to be 12 bytes long). + * high- and super-speed devices) per second and add the UVC + * header size (assumed to be 12 bytes long). */ bandwidth = frame->wWidth * frame->wHeight / 8 * format->bpp; bandwidth *= 10000000 / interval + 1; bandwidth /= 1000; - if (stream->dev->udev->speed == USB_SPEED_HIGH) + if (stream->dev->udev->speed >= USB_SPEED_HIGH) bandwidth /= 8; bandwidth += 12;
The bandwidth fixup quirk which is needed to run certain buggy cameras doesn't know that SuperSpeed exists and has the same 8 service intervals per millisecond as High Speed; hence its calculations are badly wrong. Assume that all speeds from HS up use 8 intervals per millisecond. No further changes are required. Updated code has been confirmed to work properly with a SuperSpeed camera, as well as some High Speed ones. Signed-off-by: Michal Pecio <michal.pecio@gmail.com> --- drivers/media/usb/uvc/uvc_video.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)