[libcamera-devel] [PATCH] pipeline: rpi: vc4: Allocate more embedded data buffers

[William Vinnicombe]

If the pipeline runs out of embedded data buffers, then it will pass
the frame to the IPA without the metadata. The IPA then has to use the
delayed controls as inputs to the algorithms. This can cause problems
with the subsequent algorithms if the sensor did not action the
controls, especially with the autofocus as that doesn't have controls
which can be passed in lieu of the metadata.

Reduce the likelihood of this by increasing the number of embedded data
buffers, as they are small so a generous number can be allocated.

Signed-off-by: William Vinnicombe <william.vinnicombe at raspberrypi.com>
---
 src/libcamera/pipeline/rpi/vc4/vc4.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libcamera/pipeline/rpi/vc4/vc4.cpp b/src/libcamera/pipeline/rpi/vc4/vc4.cpp
index 018cf488..6777c697 100644
--- a/src/libcamera/pipeline/rpi/vc4/vc4.cpp
+++ b/src/libcamera/pipeline/rpi/vc4/vc4.cpp
@@ -262,9 +262,9 @@ int PipelineHandlerVc4::prepareBuffers(Camera *camera)
 		} else if (stream == &data->unicam_[Unicam::Embedded]) {
 			/*
 			 * Embedded data buffers are (currently) for internal use,
-			 * so allocate the minimum required to avoid frame drops.
+			 * so allocate a generous number as they are small.
 			 */
-			numBuffers = minBuffers;
+			numBuffers = 12;
 		} else {
 			/*
 			 * Since the ISP runs synchronous with the IPA and requests,
-- 
2.39.2