[libcamera-devel] [PATCH 2/4] pipeline: raspberrypi: Use priority write for vblank when writing sensor ctrls

[Naushir Patuck]

When directly writing controls to the sensor device, ensure that VBLANK is
written ahead of and before the EXPSOURE control. This is the same priority
write mechanism used in DelayedControls.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
---
 .../pipeline/raspberrypi/raspberrypi.cpp      | 37 ++++++++++++++-----
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 887f8d0f7404..d180fc059613 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -153,6 +153,7 @@ public:
 	void embeddedComplete(uint32_t bufferId);
 	void setIspControls(const ControlList &controls);
 	void setDelayedControls(const ControlList &controls);
+	void setSensorControls(ControlList &controls);
 
 	/* bufferComplete signal handlers. */
 	void unicamBufferDequeue(FrameBuffer *buffer);
@@ -827,7 +828,7 @@ int PipelineHandlerRPi::start(Camera *camera, const ControlList *controls)
 
 	/* Apply any gain/exposure settings that the IPA may have passed back. */
 	if (!startConfig.controls.empty())
-		data->unicam_[Unicam::Image].dev()->setControls(&startConfig.controls);
+		data->setSensorControls(startConfig.controls);
 
 	/* Configure the number of dropped frames required on startup. */
 	data->dropFrameCount_ = startConfig.dropFrameCount;
@@ -1293,22 +1294,20 @@ int RPiCameraData::configureIPA(const CameraConfiguration *config)
 		return -EPIPE;
 	}
 
-	if (!controls.empty())
-		unicam_[Unicam::Image].dev()->setControls(&controls);
-
 	/*
 	 * Configure the H/V flip controls based on the combination of
 	 * the sensor and user transform.
 	 */
 	if (supportsFlips_) {
-		ControlList ctrls(unicam_[Unicam::Image].dev()->controls());
-		ctrls.set(V4L2_CID_HFLIP,
-			  static_cast<int32_t>(!!(rpiConfig->combinedTransform_ & Transform::HFlip)));
-		ctrls.set(V4L2_CID_VFLIP,
-			  static_cast<int32_t>(!!(rpiConfig->combinedTransform_ & Transform::VFlip)));
-		unicam_[Unicam::Image].dev()->setControls(&ctrls);
+		controls.set(V4L2_CID_HFLIP,
+			     static_cast<int32_t>(!!(rpiConfig->combinedTransform_ & Transform::HFlip)));
+		controls.set(V4L2_CID_VFLIP,
+			     static_cast<int32_t>(!!(rpiConfig->combinedTransform_ & Transform::VFlip)));
 	}
 
+	if (!controls.empty())
+		setSensorControls(controls);
+
 	return 0;
 }
 
@@ -1378,6 +1377,24 @@ void RPiCameraData::setDelayedControls(const ControlList &controls)
 	handleState();
 }
 
+void RPiCameraData::setSensorControls(ControlList &controls)
+{
+	/*
+	 * We need to ensure that if both VBLANK and EXPSURE are present, the
+	 * former must be written ahead of, and separately from EXPOSURE to avoid
+	 * V4L2 rejecting the latter. This is identical to what DelayedControls
+	 * does with the priority write flag.
+	 */
+	if (controls.contains(V4L2_CID_EXPOSURE) && controls.contains(V4L2_CID_VBLANK)) {
+		ControlList vblank_ctrl;
+
+		vblank_ctrl.set(V4L2_CID_VBLANK, controls.get(V4L2_CID_VBLANK));
+		unicam_[Unicam::Image].dev()->setControls(&vblank_ctrl);
+	}
+
+	unicam_[Unicam::Image].dev()->setControls(&controls);
+}
+
 void RPiCameraData::unicamBufferDequeue(FrameBuffer *buffer)
 {
 	RPi::Stream *stream = nullptr;
-- 
2.25.1