[media] uvcvideo: Add UVCIOC_CTRL_QUERY ioctl

This ioctl extends UVCIOC_CTRL_GET/SET by not only allowing to get/set
XU controls but to also send arbitrary UVC commands to XU controls,
namely GET_CUR, SET_CUR, GET_MIN, GET_MAX, GET_RES, GET_LEN, GET_INFO
and GET_DEF. This is required for applications to work with XU controls,
so that they can properly query the size and allocate the necessary
buffers.

Signed-off-by: Martin Rubli <martin_rubli@logitech.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 16 insertions, 3 deletions

diff --git a/drivers/media/video/uvc/uvc_v4l2.c b/drivers/media/video/uvc/uvc_v4l2.c
index 9005a8d9d5f8..74323362c8e6 100644
--- a/drivers/media/video/uvc/uvc_v4l2.c
+++ b/drivers/media/video/uvc/uvc_v4l2.c
@@ -1029,10 +1029,23 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
                                           cmd == UVCIOC_CTRL_MAP_OLD);
 
         case UVCIOC_CTRL_GET:
-                return uvc_xu_ctrl_query(chain, arg, 0);
-
         case UVCIOC_CTRL_SET:
-                return uvc_xu_ctrl_query(chain, arg, 1);
+        {
+                struct uvc_xu_control *xctrl = arg;
+                struct uvc_xu_control_query xqry = {
+                        .unit           = xctrl->unit,
+                        .selector       = xctrl->selector,
+                        .query          = cmd == UVCIOC_CTRL_GET
+                                        ? UVC_GET_CUR : UVC_SET_CUR,
+                        .size           = xctrl->size,
+                        .data           = xctrl->data,
+                };
+
+                return uvc_xu_ctrl_query(chain, &xqry);
+        }
+
+        case UVCIOC_CTRL_QUERY:
+                return uvc_xu_ctrl_query(chain, arg);
 
         default:
                 uvc_trace(UVC_TRACE_IOCTL, "Unknown ioctl 0x%08x\n", cmd);