Hi Guennadi,

Thank you for the patch.

On Tuesday, 8 May 2018 18:07:44 EEST Guennadi Liakhovetski wrote:
> When a command ends up in a STALL on the control pipe, use the Request
> Error Code control to provide a more precise error information to the
> user. For example, if a camera is still busy processing a control,
> when the same or an interrelated control set request arrives, the
> camera can react with a STALL and then return the "Not ready" status
> in response to a UVC_VC_REQUEST_ERROR_CODE_CONTROL command. With this
> patch the user would then get an EBUSY error code instead of a
> generic EPIPE.
> 
> Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovet...@intel.com>

Reviewed-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>

> ---
> 
> v8:
> 
> * restrict UVC_VC_REQUEST_ERROR_CODE_CONTROL to the control interface
> * fix the wIndex value
> * improve error codes
> * cosmetic changes
> 
>  drivers/media/usb/uvc/uvc_video.c | 52 +++++++++++++++++++++++++++++++-----
>  1 file changed, 46 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_video.c
> b/drivers/media/usb/uvc/uvc_video.c index aa0082f..ce65cd6 100644
> --- a/drivers/media/usb/uvc/uvc_video.c
> +++ b/drivers/media/usb/uvc/uvc_video.c
> @@ -73,17 +73,57 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8
> unit, u8 intfnum, u8 cs, void *data, u16 size)
>  {
>       int ret;
> +     u8 error;
> +     u8 tmp;
> 
>       ret = __uvc_query_ctrl(dev, query, unit, intfnum, cs, data, size,
>                               UVC_CTRL_CONTROL_TIMEOUT);
> -     if (ret != size) {
> -             uvc_printk(KERN_ERR, "Failed to query (%s) UVC control %u on "
> -                     "unit %u: %d (exp. %u).\n", uvc_query_name(query), cs,
> -                     unit, ret, size);
> -             return -EIO;
> +     if (likely(ret == size))
> +             return 0;
> +
> +     uvc_printk(KERN_ERR,
> +                "Failed to query (%s) UVC control %u on unit %u: %d (exp. 
> %u).\n",
> +                uvc_query_name(query), cs, unit, ret, size);
> +
> +     if (ret != -EPIPE)
> +             return ret;
> +
> +     tmp = *(u8 *)data;
> +
> +     ret = __uvc_query_ctrl(dev, UVC_GET_CUR, 0, intfnum,
> +                            UVC_VC_REQUEST_ERROR_CODE_CONTROL, data, 1,
> +                            UVC_CTRL_CONTROL_TIMEOUT);
> +
> +     error = *(u8 *)data;
> +     *(u8 *)data = tmp;
> +
> +     if (ret != 1)
> +             return ret < 0 ? ret : -EPIPE;
> +
> +     uvc_trace(UVC_TRACE_CONTROL, "Control error %u\n", error);
> +
> +     switch (error) {
> +     case 0:
> +             /* Cannot happen - we received a STALL */
> +             return -EPIPE;
> +     case 1: /* Not ready */
> +             return -EBUSY;
> +     case 2: /* Wrong state */
> +             return -EILSEQ;
> +     case 3: /* Power */
> +             return -EREMOTE;
> +     case 4: /* Out of range */
> +             return -ERANGE;
> +     case 5: /* Invalid unit */
> +     case 6: /* Invalid control */
> +     case 7: /* Invalid Request */
> +     case 8: /* Invalid value within range */
> +             return -EINVAL;
> +     default: /* reserved or unknown */
> +             break;
>       }
> 
> -     return 0;
> +     return -EPIPE;
>  }
> 
>  static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,

-- 
Regards,

Laurent Pinchart



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