diff mbox series

[v2,1/3] media: Documentation: Document how link frequencies can be chosen

Message ID 20231017105630.558089-2-sakari.ailus@linux.intel.com
State New
Headers show
Series Document link-frequencies better, small fixes | expand

Commit Message

Sakari Ailus Oct. 17, 2023, 10:56 a.m. UTC
Document how link frequencies can be selected for the link-frequencies
property.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
 Documentation/driver-api/media/camera-sensor.rst   | 14 ++++++++++++++
 .../userspace-api/media/drivers/camera-sensor.rst  |  2 ++
 2 files changed, 16 insertions(+)
diff mbox series

Patch

diff --git a/Documentation/driver-api/media/camera-sensor.rst b/Documentation/driver-api/media/camera-sensor.rst
index 6456145f96ed..0de5c86cbd1f 100644
--- a/Documentation/driver-api/media/camera-sensor.rst
+++ b/Documentation/driver-api/media/camera-sensor.rst
@@ -29,6 +29,20 @@  used in the system. Using another frequency may cause harmful effects
 elsewhere. Therefore only the pre-determined frequencies are configurable by the
 user.
 
+On choosing link frequencies
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Choosing link frequencies for a board is generally a part of the hardware design
+process as one needs to ensure an EMC-safe frequency the sensor supports with
+the given external clock frequency exists. On development systems this may be
+less than an immediate concern, so more or less anything that sensor and the
+rest of the applicable hardware supports can be used.
+
+If the sensor's PLL tree is not documented and all that is available are
+register lists, even knowing the frequency a driver uses may be difficult. This
+could still be :ref:`calculated from the number of lanes, sensor's output image
+size, blanking values and frame rate <media_camera_raw_frame_interval>`.
+
 ACPI
 ~~~~
 
diff --git a/Documentation/userspace-api/media/drivers/camera-sensor.rst b/Documentation/userspace-api/media/drivers/camera-sensor.rst
index 919a50e8b9d9..e0596b85e7ec 100644
--- a/Documentation/userspace-api/media/drivers/camera-sensor.rst
+++ b/Documentation/userspace-api/media/drivers/camera-sensor.rst
@@ -44,6 +44,8 @@  There are two different methods for obtaining possibilities for different frame
 intervals as well as configuring the frame interval. Which one to implement
 depends on the type of the device.
 
+.. _media_camera_raw_frame_interval:
+
 Raw camera sensors
 ~~~~~~~~~~~~~~~~~~