[PATCH v2 1/3] media: Documentation: v4l: Add CUR_LINK_FREQ control

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Add a 64-bit integer control for devices that are passing through CSI-2
(or other) data, to signal the link frequency used by also the upstream
sub-device. The control is volatile and read-only.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 .../userspace-api/media/v4l/ext-ctrls-image-process.rst      | 4 ++++
 drivers/media/v4l2-core/v4l2-ctrls-defs.c                    | 5 +++++
 include/uapi/linux/v4l2-controls.h                           | 1 +
 3 files changed, 10 insertions(+)

diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
index b1c2ab2854af..31d5045f32e7 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
@@ -55,3 +55,7 @@ Image Process Control IDs
     control value divided by e.g. 0x100, meaning that to get no
     digital gain the control value needs to be 0x100. The no-gain
     configuration is also typically the default.
+
+``V4L2_CID_CUR_LINK_FREQ (64-bit integer)``
+    The current link frequency on a data interface (e.g. parallel or
+    CSI-2). This control is read-only.
diff --git a/drivers/media/v4l2-core/v4l2-ctrls-defs.c b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
index 8696eb1cdd61..1e8e02818f9f 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-defs.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-defs.c
@@ -1163,6 +1163,7 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_TEST_PATTERN:		return "Test Pattern";
 	case V4L2_CID_DEINTERLACING_MODE:	return "Deinterlacing Mode";
 	case V4L2_CID_DIGITAL_GAIN:		return "Digital Gain";
+	case V4L2_CID_CUR_LINK_FREQ:		return "Link Frequency";
 
 	/* DV controls */
 	/* Keep the order of the 'case's the same as in v4l2-controls.h! */
@@ -1425,6 +1426,10 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
 	case V4L2_CID_LINK_FREQ:
 		*type = V4L2_CTRL_TYPE_INTEGER_MENU;
 		break;
+	case V4L2_CID_CUR_LINK_FREQ:
+		*flags |= V4L2_CTRL_FLAG_VOLATILE | V4L2_CTRL_FLAG_READ_ONLY;
+		*type = V4L2_CTRL_TYPE_INTEGER64;
+		break;
 	case V4L2_CID_RDS_TX_PS_NAME:
 	case V4L2_CID_RDS_TX_RADIO_TEXT:
 	case V4L2_CID_RDS_RX_PS_NAME:
diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h
index 99c3f5e99da7..1c63d2e51e8d 100644
--- a/include/uapi/linux/v4l2-controls.h
+++ b/include/uapi/linux/v4l2-controls.h
@@ -1223,6 +1223,7 @@ enum v4l2_jpeg_chroma_subsampling {
 #define V4L2_CID_TEST_PATTERN			(V4L2_CID_IMAGE_PROC_CLASS_BASE + 3)
 #define V4L2_CID_DEINTERLACING_MODE		(V4L2_CID_IMAGE_PROC_CLASS_BASE + 4)
 #define V4L2_CID_DIGITAL_GAIN			(V4L2_CID_IMAGE_PROC_CLASS_BASE + 5)
+#define V4L2_CID_CUR_LINK_FREQ			(V4L2_CID_IMAGE_PROC_CLASS_BASE + 6)
 
 /*  DV-class control IDs defined by V4L2 */
 #define V4L2_CID_DV_CLASS_BASE			(V4L2_CTRL_CLASS_DV | 0x900)
-- 
2.39.2