media: uvcvideo: Introduce uvc_mapping_v4l2_size

JIRA: https://issues.redhat.com/browse/RHEL-78934

commit dc6d7e0
Author: Ricardo Ribalda <ribalda@chromium.org>
Date: Mon, 3 Feb 2025 11:55:50 +0000

  Centralize the calculation for the v4l2_size of a mapping.

  Reviewed-by: Yunke Cao <yunkec@google.com>
  Tested-by: Yunke Cao <yunkec@google.com>
  Reviewed-by: Hans de Goede <hdegoede@redhat.com>
  Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
  Link: https://lore.kernel.org/r/20250203-uvc-roi-v17-14-5900a9fed613@chromium.org
  Signed-off-by: Hans de Goede <hdegoede@redhat.com>
  Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

Signed-off-by: Desnes Nunes <desnesn@redhat.com>

Author: Desnes Nunes

drivers/media/usb/uvc/uvc_ctrl.c

@@ -1471,6 +1471,14 @@ static int __uvc_queryctrl_boundaries(struct uvc_video_chain *chain,
 	return 0;
 }
 
+static size_t uvc_mapping_v4l2_size(struct uvc_control_mapping *mapping)
+{
+	if (uvc_ctrl_mapping_is_compound(mapping))
+		return DIV_ROUND_UP(mapping->size, 8);
+
+	return sizeof(s32);
+}
+
 static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 				 struct uvc_control *ctrl,
 				 struct uvc_control_mapping *mapping,
@@ -1512,7 +1520,7 @@ static int __uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 			v4l2_ctrl->flags |= V4L2_CTRL_FLAG_INACTIVE;
 	}
 
-	v4l2_ctrl->elem_size = sizeof(s32);
+	v4l2_ctrl->elem_size = uvc_mapping_v4l2_size(mapping);
 	v4l2_ctrl->elems = 1;
 
 	if (v4l2_ctrl->type >= V4L2_CTRL_COMPOUND_TYPES) {
@@ -2144,7 +2152,7 @@ static int uvc_mapping_get_xctrl_compound(struct uvc_video_chain *chain,
 		return -EINVAL;
 	}
 
-	size = DIV_ROUND_UP(mapping->size, 8);
+	size = uvc_mapping_v4l2_size(mapping);
 	if (xctrl->size < size) {
 		xctrl->size = size;
 		return -ENOSPC;
@@ -2327,9 +2335,8 @@ static int uvc_mapping_set_xctrl_compound(struct uvc_control *ctrl,
 					  struct v4l2_ext_control *xctrl)
 {
 	u8 *data __free(kfree) = NULL;
-	size_t size;
+	size_t size = uvc_mapping_v4l2_size(mapping);
 
-	size = DIV_ROUND_UP(mapping->size, 8);
 	if (xctrl->size != size)
 		return -EINVAL;