media: uvcvideo: Handle control pipe protocol STALLs

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>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 3ed5f27..86a99f4 100644 (file)
--- 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,