[libcamera-devel] [PATCH v5 08/12] pipeline: raspberrypi: Handle OptionalStream hints for ISP Output0

[Naushir Patuck]

Look for OptionalStream flag in the hints field of the ISP Output0
StreamConfiguration structure. If this flag is not set, it guarantees that the
application will provide buffers for the ISP, do not allocate any internal
buffers for the device.

Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
---
 .../pipeline/raspberrypi/raspberrypi.cpp      | 29 ++++++++++++++-----
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 2b396f1db9b6..13d0ab4c4968 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -1453,7 +1453,7 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 	RPiCameraData *data = cameraData(camera);
 	unsigned int minUnicamBuffers = data->config_.minUnicamBuffers,
 		     minTotalUnicamBuffers = data->config_.minTotalUnicamBuffers,
-		     numRawBuffers = 0;
+		     numRawBuffers = 0, minIspBuffers = 1;
 	int ret;
 
 	for (Stream *s : camera->streams()) {
@@ -1477,8 +1477,21 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 					minTotalUnicamBuffers = 0;
 				}
 			}
-
-			break;
+		} else if (s == &data->isp_[Isp::Output0]) {
+			/*
+			 * Since the ISP runs synchronous with the IPA and requests,
+			 * we only ever need a maximum of one internal buffer. Any
+			 * buffers the application wants to hold onto will already
+			 * be exported through PipelineHandlerRPi::exportFrameBuffers().
+			 *
+			 * However, as above, if the application provides a guarantee
+			 * that the buffer will always be provided for the ISP Output0
+			 * stream in a Request, we don't need any internal buffers
+			 * allocated.
+			 */
+			if (!(s->configuration().hints & StreamConfiguration::Hint::OptionalStream) &&
+			    !data->dropFrameCount_)
+				minIspBuffers = 0;
 		}
 	}
 
@@ -1514,12 +1527,14 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 			 * so allocate the minimum required to avoid frame drops.
 			 */
 			numBuffers = data->config_.minTotalUnicamBuffers;
+		} else if (stream == &data->isp_[Isp::Output0]) {
+			/* Buffer count for this is handled in the earlier loop above. */
+			numBuffers = minIspBuffers;
 		} else {
 			/*
-			 * Since the ISP runs synchronous with the IPA and requests,
-			 * we only ever need one set of internal buffers. Any buffers
-			 * the application wants to hold onto will already be exported
-			 * through PipelineHandlerRPi::exportFrameBuffers().
+			 * Same reasoning as for ISP Output 0, we only ever need
+			 * a maximum of one internal buffer for Output1 (required
+			 * for colour denoise) and ISP statistics.
 			 */
 			numBuffers = 1;
 		}
-- 
2.25.1