Hi Philipp, Laurent, On 02/02/2014 02:04 PM, Philipp Zabel wrote: > On Sun, Feb 02, 2014 at 11:21:13AM +0100, Laurent Pinchart wrote: >> Hi Hans, >> >> On Friday 31 January 2014 09:43:00 Hans Verkuil wrote: >>> I think you might want to add a check in uvc_queue_setup to verify the >>> fmt that create_bufs passes. The spec says that: "Unsupported formats >>> will result in an error". In this case I guess that the format basically >>> should match the current selected format. >>> >>> I'm unhappy with the current implementations of create_bufs (see also this >>> patch: >>> http://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg70796.html). >>> >>> Nobody is actually checking the format today, which isn't good. >>> >>> The fact that the spec says that the fmt field isn't changed by the driver >>> isn't helping as it invalidated my patch from above, although that can be >>> fixed. >>> >>> I need to think about this some more, but for this particular case you can >>> just do a memcmp of the v4l2_pix_format against the currently selected >>> format and return an error if they differ. Unless you want to support >>> different buffer sizes as well? >> >> Isn't the whole point of VIDIOC_CREATE_BUFS being able to create buffers of >> different resolutions than the current active resolution ? Or just additional buffers with the same resolution (or really, the same size). > For that to work the driver in question would need to keep track of per-buffer > format and resolution, and not only of per-queue format and resolution. > > For now, would something like the following be enough? Unfortunately the uvc > driver doesn't keep a v4l2_format around that we could just memcmp against: > > diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c > index fa58131..7fa469b 100644 > --- a/drivers/media/usb/uvc/uvc_v4l2.c > +++ b/drivers/media/usb/uvc/uvc_v4l2.c > @@ -1003,10 +1003,26 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg) > case VIDIOC_CREATE_BUFS: > { > struct v4l2_create_buffers *cb = arg; > + struct v4l2_pix_format *pix; > + struct uvc_format *format; > + struct uvc_frame *frame; > > if (!uvc_has_privileges(handle)) > return -EBUSY; > > + format = stream->cur_format; > + frame = stream->cur_frame; > + pix = &cb->format.fmt.pix; > + > + if (pix->pixelformat != format->fcc || > + pix->width != frame->wWidth || > + pix->height != frame->wHeight || > + pix->field != V4L2_FIELD_NONE || > + pix->bytesperline != format->bpp * frame->wWidth / 8 || > + pix->sizeimage != stream->ctrl.dwMaxVideoFrameSize || > + pix->colorspace != format->colorspace) I would drop the field and colorspace checks (those do not really affect any size calculations), other than that it looks good. Regards, Hans > + return -EINVAL; > + > return uvc_create_buffers(&stream->queue, cb); > } > > > regards > Philipp > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
