[libcamera-devel] [PATCH v1 07/10] pipeline: raspberrypi: Add a parameter to disable startup drop frames

[Naushir Patuck]

Add a new pipeline config parameter "disable_startup_frame_drops" to disable
any startup drop frames, overriding the IPA request.

When this parameter is set, it allows the pipeline handler to run with no
internally allocated Unicam buffers ("min_unicam_buffers").

Add a validation to ensure if "disable_startup_frame_drops" is false, at least
one internal Unicam buffer is allocated, possibly overriding the
"min_unicam_buffers" parameter.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
---
 .../pipeline/raspberrypi/data/default.json        |  7 +++++--
 .../pipeline/raspberrypi/raspberrypi.cpp          | 15 ++++++++++++++-
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/libcamera/pipeline/raspberrypi/data/default.json b/src/libcamera/pipeline/raspberrypi/data/default.json
index a7ea735c87f4..707414bcc5c5 100644
--- a/src/libcamera/pipeline/raspberrypi/data/default.json
+++ b/src/libcamera/pipeline/raspberrypi/data/default.json
@@ -5,7 +5,7 @@
         "pipeline_handler":
         {
                 # The minimum number of internal buffers to be allocated for Unicam.
-                # This value must be greater than 0, but less than or equal to min_total_unicam_buffers.
+                # This value must less than or equal to min_total_unicam_buffers.
                 "min_unicam_buffers": 2,
 
                 # The minimum total (internal + external) buffer count used for Unicam.
@@ -15,6 +15,9 @@
                 "min_total_unicam_buffers": 4,
                 
                 # The number of internal buffers used for ISP Output0.
-                "num_output0_buffers": 1
+                "num_output0_buffers": 1,
+
+                # Override any request from the IPA to drop a number of startup frames.
+                "disable_startup_frame_drops": false
         }
 }
diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 2aba0430c02e..135948d82f41 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -300,6 +300,7 @@ public:
 		unsigned int minUnicamBuffers;
 		unsigned int minTotalUnicamBuffers;
 		unsigned int numOutput0Buffers;
+		bool disableStartupFrameDrops;
 	};
 
 	Config config_;
@@ -1044,7 +1045,7 @@ int PipelineHandlerRPi::start(Camera *camera, const ControlList *controls)
 		data->setSensorControls(startConfig.controls);
 
 	/* Configure the number of dropped frames required on startup. */
-	data->dropFrameCount_ = startConfig.dropFrameCount;
+	data->dropFrameCount_ = data->config_.disableStartupFrameDrops ? 0 : startConfig.dropFrameCount;
 
 	for (auto const stream : data->streams_)
 		stream->resetBuffers();
@@ -1430,6 +1431,7 @@ int PipelineHandlerRPi::configurePipelineHandler(RPiCameraData *data)
 		.minUnicamBuffers = 2,
 		.minTotalUnicamBuffers = 4,
 		.numOutput0Buffers = 1,
+		.disableStartupFrameDrops = false,
 	};
 
 	char const *configFromEnv = utils::secure_getenv("LIBCAMERA_RPI_CONFIG_FILE");
@@ -1464,6 +1466,8 @@ int PipelineHandlerRPi::configurePipelineHandler(RPiCameraData *data)
 		phConfig["min_total_unicam_buffers"].get<unsigned int>(config.minTotalUnicamBuffers);
 	config.numOutput0Buffers =
 		phConfig["num_output0_buffers"].get<unsigned int>(config.numOutput0Buffers);
+	config.disableStartupFrameDrops =
+		phConfig["disable_startup_frame_drops"].get<bool>(config.disableStartupFrameDrops);
 
 	if (config.minTotalUnicamBuffers < config.minUnicamBuffers || config.minTotalUnicamBuffers < 1) {
 		LOG(RPI, Error) << "Invalid Unicam buffer configuration used!";
@@ -1543,6 +1547,15 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 			 */
 			numBuffers = std::max<int>(data->config_.minUnicamBuffers,
 						   minBuffers - numRawBuffers);
+
+			if (numBuffers == 0 && data->dropFrameCount_) {
+				LOG(RPI, Warning)
+					<< "Configured with no Unicam buffers,"
+					   " but the IPA requested startup frame drops."
+					   " Increasing to one buffer.";
+				numBuffers = 1;
+			}
+
 			data->numUnicamBuffers = numBuffers;
 		} else if (stream == &data->isp_[Isp::Input]) {
 			/*
-- 
2.25.1