[libcamera-devel] [RFC PATCH v3 04/16] android, controls: Add and plumb MaxLatency control

[Paul Elder]

Add a MaxLatency control, and plumb it into the HAL accordingly.

Bug: https://bugs.libcamera.org/show_bug.cgi?id=50
Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

---
Changes in v3:
- use v3 setMetadata
- add comment to explain 4
- remove todo

Changes in v2:
- use new setMetadata
- rebase on camera capabilities refactor
---
 src/android/camera_capabilities.cpp | 13 +++++++++++--
 src/libcamera/control_ids.yaml      | 10 ++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
index 1d4c44ce..530167de 100644
--- a/src/android/camera_capabilities.cpp
+++ b/src/android/camera_capabilities.cpp
@@ -870,8 +870,17 @@ int CameraCapabilities::initializeStaticMetadata()
 	}
 
 	/* Sync static metadata. */
-	int32_t maxLatency = ANDROID_SYNC_MAX_LATENCY_UNKNOWN;
-	staticMetadata_->addEntry(ANDROID_SYNC_MAX_LATENCY, maxLatency);
+	int32_t maxLatency = setMetadata<int32_t, int32_t>(
+		staticMetadata_.get(), ANDROID_SYNC_MAX_LATENCY,
+		controlsInfo, &controls::draft::MaxLatency,
+		ControlRange::Def,
+		(int32_t)ANDROID_SYNC_MAX_LATENCY_UNKNOWN);
+	LOG(HAL, Info) << "Max sync latency is " << maxLatency;
+	/* CTS allows a sync latency of up to 4 for burst capture capability */
+	if (maxLatency < 0 || 4 < maxLatency)
+		capabilities.erase(ANDROID_REQUEST_AVAILABLE_CAPABILITIES_BURST_CAPTURE);
+	if (maxLatency != 0)
+		hwLevels.erase(ANDROID_INFO_SUPPORTED_HARDWARE_LEVEL_FULL);
 
 	/* Flash static metadata. */
 	char flashAvailable = ANDROID_FLASH_INFO_AVAILABLE_FALSE;
diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
index d92f29f5..9d4638ae 100644
--- a/src/libcamera/control_ids.yaml
+++ b/src/libcamera/control_ids.yaml
@@ -622,6 +622,16 @@ controls:
         detection, additional format conversions etc) count as an additional
         pipeline stage.
 
+  - MaxLatency:
+      type: int32_t
+      draft: true
+      description: |
+        The maximum number of frames that can occur after a request (different
+        than the previous) has been submitted, and before the result's state
+        becomes synchronized. A value of -1 indicates unknown latency, and 0
+        indicates per-frame control. Currently identical to
+        ANDROID_SYNC_MAX_LATENCY.
+
   - TestPatternMode:
       type: int32_t
       draft: true
-- 
2.27.0