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 ? 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) + 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
