[PATCH v4 1/6] libcamera: controls: Update the ColourTemperature control to be writable

[Stefan Klug]

For manual control it is helpful to be able to specify a fixed colour
temperature. It also provides an easy way to apply the temperature
specific CCMs and colour gains that are contained in the tuning files.

Document this and update the control dependencies.

Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
---
 src/libcamera/control_ids_core.yaml | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/libcamera/control_ids_core.yaml b/src/libcamera/control_ids_core.yaml
index cf40771d3896..04dcc4af67fc 100644
--- a/src/libcamera/control_ids_core.yaml
+++ b/src/libcamera/control_ids_core.yaml
@@ -252,9 +252,12 @@ controls:
   - AwbEnable:
       type: bool
       description: |
-        Enable or disable the AWB.
+        Enable or disable the AWB. Disabling AWB stops updates to the
+        ColourGains and to the ColourCorrectionMatrix.
 
+        \sa ColourCorrectionMatrix
         \sa ColourGains
+        \sa ColourTemperature
 
   # AwbMode needs further attention:
   # - Auto-generate max enum value.
@@ -309,13 +312,24 @@ controls:
         disabled.
 
         \sa AwbEnable
+        \sa ColourTemperature
       size: [2]
 
   - ColourTemperature:
       type: int32_t
-      description: Report the current estimate of the colour temperature, in
-        kelvin, for this frame. The ColourTemperature control can only be
-        returned in metadata.
+      description: |
+        Report the current estimate of the colour temperature, in kelvin, for
+        this frame. An implementation may also allow this control to be set when
+        AWB is disabled. In that case ColourGains and the ColourCorrectionMatrix
+        get set accordingly. If either ColourGains or ColourCorrectionMatrix are
+        specified at the same time, they take precedence.
+
+        The metadata will only report measured colour temperature values when
+        available, even if set manually.
+
+        \sa AwbEnable
+        \sa ColourCorrectionMatrix
+        \sa ColourGains
 
   - Saturation:
       type: float
@@ -365,6 +379,8 @@ controls:
         transformation. The 3x3 matrix is stored in conventional reading
         order in an array of 9 floating point values.
 
+        \sa AwbEnable
+        \sa ColourTemperature
       size: [3,3]
 
   - ScalerCrop:
-- 
2.43.0