media: v4l: uapi: ccs: Add CCS controls for shading correction

Add V4L2 controls for controlling CCS lens shading correction as well as
conveying its capabilities.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/Documentation/userspace-api/media/drivers/ccs.rst b/Documentation/userspace-api/media/drivers/ccs.rst
index ea09c8139c23..161cb65f4d98 100644
--- a/Documentation/userspace-api/media/drivers/ccs.rst
+++ b/Documentation/userspace-api/media/drivers/ccs.rst
@@ -94,4 +94,17 @@ The ``linear`` and ``exponent`` factors can be set using the
 ``V4L2_CID_CCS_ANALOGUE_LINEAR_GAIN`` and
 ``V4L2_CID_CCS_ANALOGUE_EXPONENTIAL_GAIN`` controls, respectively
 
+Shading correction
+~~~~~~~~~~~~~~~~~~
+
+The CCS standard supports lens shading correction. The feature can be controlled
+using ``V4L2_CID_CCS_SHADING_CORRECTION``. Additionally, the luminance
+correction level may be changed using
+``V4L2_CID_CCS_LUMINANCE_CORRECTION_LEVEL``, where value 0 indicates no
+correction and 128 indicates correcting the luminance in corners to 10 % less
+than in the centre.
+
+Shading correction needs to be enabled for luminance correction level to have an
+effect.
+
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