controls: Introduce AEGC-related controls

Introduce the AeState, ExposureTimeMode and AnalogueGainMode controls
to model the AEGC algorithm block.

The three controls allow applications to select the exposure time and
analogue gain computation calculation mode (auto vs manual)
independently from one another, while the AeState control reports the
global state for the AEGC algorithm.

The new controls are meant to replace the existing AeEnable and AeLocked
controls, which are momentarily kept not to break compilation of
platforms making use of them.

Bug: https://bugs.libcamera.org/show_bug.cgi?id=42
Bug: https://bugs.libcamera.org/show_bug.cgi?id=43
Bug: https://bugs.libcamera.org/show_bug.cgi?id=47
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/libcamera/control_ids_draft.yaml

@@ -80,36 +80,6 @@ controls:
             High quality aberration correction which might reduce the frame
             rate.
 
-  - AeState:
-      type: int32_t
-      direction: out
-      description: |
-       Control to report the current AE algorithm state. Currently identical to
-       ANDROID_CONTROL_AE_STATE.
-
-        Current state of the AE algorithm.
-      enum:
-        - name: AeStateInactive
-          value: 0
-          description: The AE algorithm is inactive.
-        - name: AeStateSearching
-          value: 1
-          description: The AE algorithm has not converged yet.
-        - name: AeStateConverged
-          value: 2
-          description: The AE algorithm has converged.
-        - name: AeStateLocked
-          value: 3
-          description: The AE algorithm is locked.
-        - name: AeStateFlashRequired
-          value: 4
-          description: The AE algorithm would need a flash for good results
-        - name: AeStatePrecapture
-          value: 5
-          description: |
-            The AE algorithm has started a pre-capture metering session.
-            \sa AePrecaptureTrigger
-
   - AwbState:
       type: int32_t
       direction: out