Re: [PATCH 0/8] usb: gadget: uvc: fix errors reported by v4l2-compliance

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Michael,

On Thu, Mar 23, 2023 at 12:41:09PM +0100, Michael Tretter wrote:
> This series fixes various errors and warnings that are reported by
> v4l2-compliance for the v4l2 output device created by the UVC gadget.
> 
> Most notably, it changes the driver to take the initial format from the
> configfs instead of using a hard coded value that might be rejected later in
> the SET_FORMAT call. Note that user space is still responsible for negotiating
> the format with the UVC host.

I'm afraid I dislike most of this series (apart from the fix to
REQBUFS). It was a bad idea to add format handling to the driver in the
first place, and this series adds up code on top of that to please a
compliance tool but without any added value. This code should never be
exercised by userspace and will just bloat the kernel. That's not good.
I'd recommend reverting the series that add format handling if you want
to improve the UVC gadget driver.

> To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> To: Daniel Scally <dan.scally@ideasonboard.com>
> To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>
> Cc: linux-usb@vger.kernel.org
> Cc: linux-media@vger.kernel.org
> Cc: kernel@pengutronix.de
> Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
> 
> ---
> Michael Tretter (8):
>       usb: gadget: uvc: use fourcc printk helper
>       usb: gadget: uvc: fix return code of REQBUFS
>       usb: gadget: uvc: implement s/g_output ioctl
>       usb: gadget: uvc: move video format initialization to uvc_v4l2
>       usb: gadget: uvc: initialize video format using configfs
>       usb: gadget: uvc: try harder to find a valid format
>       usb: gadget: uvc: add colorspace handling
>       usb: gadget: uvc: implement s/g_parm
> 
>  drivers/usb/gadget/function/f_uvc.c     |   2 +
>  drivers/usb/gadget/function/uvc.h       |   5 +
>  drivers/usb/gadget/function/uvc_queue.c |   6 +-
>  drivers/usb/gadget/function/uvc_v4l2.c  | 235 ++++++++++++++++++++++++++++++--
>  drivers/usb/gadget/function/uvc_v4l2.h  |   3 +
>  drivers/usb/gadget/function/uvc_video.c |   5 -
>  6 files changed, 238 insertions(+), 18 deletions(-)
> ---
> base-commit: 8be174835f07b2c106b9961c0775486d06112a3c
> change-id: 20230323-uvc-gadget-cleanup-47b1495befb9

-- 
Regards,

Laurent Pinchart