[PATCH v5 1/1] media: Documentation: Improve LINK_FREQ documentation

[PATCH v5 1/1] media: Documentation: Improve LINK_FREQ documentation

[Sakari Ailus]

Add a reference to the LINK_FREQ control and clarify the meaning of the
control as for C-PHY the matter is less obvious.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Mirela Rabulea <mirela.rabulea@nxp.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
I'm posting this separately from the metadata preparation series.

since v4 metadata preparation:

- Add the dependency to UI for CSI-2.

 Documentation/driver-api/media/tx-rx.rst                     | 3 ++-
 .../userspace-api/media/v4l/ext-ctrls-image-process.rst      | 5 ++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/driver-api/media/tx-rx.rst b/Documentation/driver-api/media/tx-rx.rst
index 22e1b13ecde9..7df2407817b3 100644
--- a/Documentation/driver-api/media/tx-rx.rst
+++ b/Documentation/driver-api/media/tx-rx.rst
@@ -93,7 +93,8 @@ where
    * - variable or constant
      - description
    * - link_freq
-     - The value of the ``V4L2_CID_LINK_FREQ`` integer64 menu item.
+     - The value of the :ref:`V4L2_CID_LINK_FREQ <v4l2-cid-link-freq>` integer64
+       menu item.
    * - nr_of_lanes
      - Number of data lanes used on the CSI-2 link.
    * - 2
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 6d516f041ca2..57c2baf34acf 100644
--- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
+++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
@@ -24,7 +24,10 @@ Image Process Control IDs
 .. _v4l2-cid-link-freq:
 
 ``V4L2_CID_LINK_FREQ (integer menu)``
-    The frequency of the data bus (e.g. parallel or CSI-2).
+    The fundamental frequency of the operating symbol rate (serial interfaces
+    such as CSI-2) or the sampling rate (parallel interfaces such as DVP or
+    Bt.565) of the data interface. For CSI-2, the frequency is equal to
+    _1 / (2 * UI)_.
 
 .. _v4l2-cid-pixel-rate:
 
-- 
2.47.3

Re: [PATCH v5 1/1] media: Documentation: Improve LINK_FREQ documentation

[Laurent Pinchart]

On Thu, May 07, 2026 at 01:10:52PM +0300, Sakari Ailus wrote:
> Add a reference to the LINK_FREQ control and clarify the meaning of the
> control as for C-PHY the matter is less obvious.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Reviewed-by: Mirela Rabulea <mirela.rabulea@nxp.com>
> Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> I'm posting this separately from the metadata preparation series.
> 
> since v4 metadata preparation:
> 
> - Add the dependency to UI for CSI-2.
> 
>  Documentation/driver-api/media/tx-rx.rst                     | 3 ++-
>  .../userspace-api/media/v4l/ext-ctrls-image-process.rst      | 5 ++++-
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/driver-api/media/tx-rx.rst b/Documentation/driver-api/media/tx-rx.rst
> index 22e1b13ecde9..7df2407817b3 100644
> --- a/Documentation/driver-api/media/tx-rx.rst
> +++ b/Documentation/driver-api/media/tx-rx.rst
> @@ -93,7 +93,8 @@ where
>     * - variable or constant
>       - description
>     * - link_freq
> -     - The value of the ``V4L2_CID_LINK_FREQ`` integer64 menu item.
> +     - The value of the :ref:`V4L2_CID_LINK_FREQ <v4l2-cid-link-freq>` integer64
> +       menu item.
>     * - nr_of_lanes
>       - Number of data lanes used on the CSI-2 link.
>     * - 2
> 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 6d516f041ca2..57c2baf34acf 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-image-process.rst
> @@ -24,7 +24,10 @@ Image Process Control IDs
>  .. _v4l2-cid-link-freq:
>  
>  ``V4L2_CID_LINK_FREQ (integer menu)``
> -    The frequency of the data bus (e.g. parallel or CSI-2).
> +    The fundamental frequency of the operating symbol rate (serial interfaces
> +    such as CSI-2) or the sampling rate (parallel interfaces such as DVP or
> +    Bt.565) of the data interface. For CSI-2, the frequency is equal to
> +    _1 / (2 * UI)_.
>  
>  .. _v4l2-cid-pixel-rate:
>  

-- 
Regards,

Laurent Pinchart