[libcamera-devel] [PATCH v3 1/5] libcamera: controls: Updates to gain and exposure controls

[Naushir Patuck]

Rename:
ManualExposure -> ExposureTime
ManualGain -> AnalogueGain

Use micro-seconds units for ExposureTime. This is changed from milli-
seconds. The latter would not allow very low exposure times.

AnalogueGain switch to use a float to allow fractional gain adjustments.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
---
 src/libcamera/control_ids.yaml               | 20 ++++++++++++++------
 src/libcamera/pipeline/uvcvideo/uvcvideo.cpp |  8 ++++----
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
index 4befec74..839eea76 100644
--- a/src/libcamera/control_ids.yaml
+++ b/src/libcamera/control_ids.yaml
@@ -10,7 +10,7 @@ controls:
       description: |
         Enable or disable the AE.
 
-        \sa ManualExposure
+        \sa ExposureTime AnalogueGain
 
   - AeLocked:
       type: bool
@@ -42,12 +42,20 @@ controls:
       type: int32_t
       description: Specify a fixed saturation parameter
 
-  - ManualExposure:
+  - ExposureTime:
       type: int32_t
-      description: Specify a fixed exposure time in milli-seconds
+      description: |
+        Exposure time (shutter speed) for the frame applied in the sensor
+        device. This value is specified in micro-seconds.
 
-  - ManualGain:
-      type: int32_t
-      description: Specify a fixed gain parameter
+        \sa AnalogueGain AeEnable
+
+  - AnalogueGain:
+      type: float
+      description: |
+        Analogue gain value applied in the sensor device.
+        The value of the control specifies the gain multiplier applied to all
+        colour channels. This value cannot be lower than 1.0.
 
+        \sa ExposureTime AeEnable
 ...
diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
index ffbddf27..d7df95e4 100644
--- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
@@ -251,10 +251,10 @@ int PipelineHandlerUVC::processControls(UVCCameraData *data, Request *request)
 			controls.set(V4L2_CID_CONTRAST, value);
 		} else if (id == controls::Saturation) {
 			controls.set(V4L2_CID_SATURATION, value);
-		} else if (id == controls::ManualExposure) {
+		} else if (id == controls::ExposureTime) {
 			controls.set(V4L2_CID_EXPOSURE_AUTO, static_cast<int32_t>(1));
 			controls.set(V4L2_CID_EXPOSURE_ABSOLUTE, value);
-		} else if (id == controls::ManualGain) {
+		} else if (id == controls::AnalogueGain) {
 			controls.set(V4L2_CID_GAIN, value);
 		}
 	}
@@ -364,10 +364,10 @@ int UVCCameraData::init(MediaEntity *entity)
 			id = &controls::Saturation;
 			break;
 		case V4L2_CID_EXPOSURE_ABSOLUTE:
-			id = &controls::ManualExposure;
+			id = &controls::ExposureTime;
 			break;
 		case V4L2_CID_GAIN:
-			id = &controls::ManualGain;
+			id = &controls::AnalogueGain;
 			break;
 		default:
 			continue;
-- 
2.17.1