Re: [PATCH v8 3/3] uvcvideo: handle control pipe protocol STALLs

Laurent Pinchart
2018-07-17T23:51:56Z

Hi Guennadi,

On Tuesday, 17 July 2018 23:58:03 EEST Laurent Pinchart wrote:
> 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.liakhovetski@intel.com>
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Can I push this patch already before 2/3 is ready ?

> > ---
> >
> > 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