[PATCH v7 2/7] media: uvcvideo: add uvc_ctrl_get_fixed for getting default value

[Yunke Cao <yunkec@google.com>]

Introduce a new uvc_ctrl_get_fixed. It simply calls query_v4l2_ctrl()
for now, but is easier to extend to support compound controls and
V4L2_CTRL_WHICH_MIN/MAX_VAL in the following patches.

Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Yunke Cao <yunkec@google.com>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 13 +++++++++++++
 drivers/media/usb/uvc/uvc_v4l2.c |  6 +-----
 drivers/media/usb/uvc/uvcvideo.h |  2 ++
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 0e78233fc8a0..772d9d28a520 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1697,6 +1697,19 @@ int uvc_ctrl_get(struct uvc_video_chain *chain,
 	return __uvc_ctrl_get(chain, ctrl, mapping, &xctrl->value);
 }
 
+int uvc_ctrl_get_fixed(struct uvc_video_chain *chain,
+		       struct v4l2_ext_control *xctrl)
+{
+	struct v4l2_queryctrl qc = { .id = xctrl->id };
+	int ret = uvc_query_v4l2_ctrl(chain, &qc);
+
+	if (ret < 0)
+		return ret;
+
+	xctrl->value = qc.default_value;
+	return 0;
+}
+
 int uvc_ctrl_set(struct uvc_fh *handle,
 	struct v4l2_ext_control *xctrl)
 {
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 648dcd579e81..0366d05895a9 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -1042,15 +1042,11 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
 
 	if (ctrls->which == V4L2_CTRL_WHICH_DEF_VAL) {
 		for (i = 0; i < ctrls->count; ++ctrl, ++i) {
-			struct v4l2_queryctrl qc = { .id = ctrl->id };
-
-			ret = uvc_query_v4l2_ctrl(chain, &qc);
+			ret = uvc_ctrl_get_fixed(chain, ctrl);
 			if (ret < 0) {
 				ctrls->error_idx = i;
 				return ret;
 			}
-
-			ctrl->value = qc.default_value;
 		}
 
 		return 0;
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index c5b4febd2d94..ba028ba7c34e 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -901,6 +901,8 @@ static inline int uvc_ctrl_rollback(struct uvc_fh *handle)
 }
 
 int uvc_ctrl_get(struct uvc_video_chain *chain, struct v4l2_ext_control *xctrl);
+int uvc_ctrl_get_fixed(struct uvc_video_chain *chain,
+		       struct v4l2_ext_control *xctrl);
 int uvc_ctrl_set(struct uvc_fh *handle, struct v4l2_ext_control *xctrl);
 int uvc_ctrl_is_accessible(struct uvc_video_chain *chain, u32 v4l2_id,
 			   bool read);
-- 
2.37.0.rc0.161.g10f37bed90-goog