media: uvcvideo: Set error_idx during ctrl_commit errors

If we have an error setting a control, return the affected control in
the error_idx field.

Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

Author: ribalda

drivers/media/usb/uvc/uvc_ctrl.c

@@ -1582,7 +1582,7 @@ int uvc_ctrl_begin(struct uvc_video_chain *chain)
 }
 
 static int uvc_ctrl_commit_entity(struct uvc_device *dev,
-	struct uvc_entity *entity, int rollback)
+	struct uvc_entity *entity, int rollback, struct uvc_control **err_ctrl)
 {
 	struct uvc_control *ctrl;
 	unsigned int i;
@@ -1624,31 +1624,59 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev,
 
 		ctrl->dirty = 0;
 
-		if (ret < 0)
+		if (ret < 0) {
+			if (err_ctrl)
+				*err_ctrl = ctrl;
 			return ret;
+		}
 	}
 
 	return 0;
 }
 
+static int uvc_ctrl_find_ctrl_idx(struct uvc_entity *entity,
+				  struct v4l2_ext_controls *ctrls,
+				  struct uvc_control *uvc_control)
+{
+	struct uvc_control_mapping *mapping;
+	struct uvc_control *ctrl_found;
+	unsigned int i;
+
+	if (!entity)
+		return ctrls->count;
+
+	for (i = 0; i < ctrls->count; i++) {
+		__uvc_find_control(entity, ctrls->controls[i].id, &mapping,
+				   &ctrl_found, 0);
+		if (uvc_control == ctrl_found)
+			return i;
+	}
+
+	return ctrls->count;
+}
+
 int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
-		      const struct v4l2_ext_control *xctrls,
-		      unsigned int xctrls_count)
+		      struct v4l2_ext_controls *ctrls)
 {
 	struct uvc_video_chain *chain = handle->chain;
+	struct uvc_control *err_ctrl;
 	struct uvc_entity *entity;
 	int ret = 0;
 
 	/* Find the control. */
 	list_for_each_entry(entity, &chain->entities, chain) {
-		ret = uvc_ctrl_commit_entity(chain->dev, entity, rollback);
+		ret = uvc_ctrl_commit_entity(chain->dev, entity, rollback,
+					     &err_ctrl);
 		if (ret < 0)
 			goto done;
 	}
 
 	if (!rollback)
-		uvc_ctrl_send_events(handle, xctrls, xctrls_count);
+		uvc_ctrl_send_events(handle, ctrls->controls, ctrls->count);
 done:
+	if (ret < 0 && ctrls)
+		ctrls->error_idx = uvc_ctrl_find_ctrl_idx(entity, ctrls,
+							  err_ctrl);
 	mutex_unlock(&chain->ctrl_mutex);
 	return ret;
 }
@@ -2106,7 +2134,7 @@ int uvc_ctrl_restore_values(struct uvc_device *dev)
 			ctrl->dirty = 1;
 		}
 
-		ret = uvc_ctrl_commit_entity(dev, entity, 0);
+		ret = uvc_ctrl_commit_entity(dev, entity, 0, NULL);
 		if (ret < 0)
 			return ret;
 	}

drivers/media/usb/uvc/uvc_v4l2.c

@@ -1100,7 +1100,7 @@ static int uvc_ioctl_s_try_ext_ctrls(struct uvc_fh *handle,
 	ctrls->error_idx = 0;
 
 	if (ioctl == VIDIOC_S_EXT_CTRLS)
-		return uvc_ctrl_commit(handle, ctrls->controls, ctrls->count);
+		return uvc_ctrl_commit(handle, ctrls);
 	else
 		return uvc_ctrl_rollback(handle);
 }

drivers/media/usb/uvc/uvcvideo.h

@@ -886,17 +886,15 @@ void uvc_ctrl_status_event(struct uvc_video_chain *chain,
 
 int uvc_ctrl_begin(struct uvc_video_chain *chain);
 int __uvc_ctrl_commit(struct uvc_fh *handle, int rollback,
-		      const struct v4l2_ext_control *xctrls,
-		      unsigned int xctrls_count);
+		      struct v4l2_ext_controls *ctrls);
 static inline int uvc_ctrl_commit(struct uvc_fh *handle,
-				  const struct v4l2_ext_control *xctrls,
-				  unsigned int xctrls_count)
+				  struct v4l2_ext_controls *ctrls)
 {
-	return __uvc_ctrl_commit(handle, 0, xctrls, xctrls_count);
+	return __uvc_ctrl_commit(handle, 0, ctrls);
 }
 static inline int uvc_ctrl_rollback(struct uvc_fh *handle)
 {
-	return __uvc_ctrl_commit(handle, 1, NULL, 0);
+	return __uvc_ctrl_commit(handle, 1, NULL);
 }
 
 int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control *xctrl);