[libcamera-devel] [PATCH v6 08/15] pipeline: raspberrypi: Handle MandatoryStream hints for ISP Output0

[Naushir Patuck]

Look for MandatoryStream flag in the hints field of the ISP Output0
StreamConfiguration structure. If this flag is 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>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.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 83e82bd2880d..7c6db070dfc0 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -1457,7 +1457,7 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
 	RPiCameraData *data = cameraData(camera);
 	unsigned int minUnicamBuffers = data->config_.minUnicamBuffers;
 	unsigned int minTotalUnicamBuffers = data->config_.minTotalUnicamBuffers;
-	unsigned int numRawBuffers = 0;
+	unsigned int numRawBuffers = 0, minIspBuffers = 1;
 	int ret;
 
 	for (Stream *s : camera->streams()) {
@@ -1481,8 +1481,21 @@ 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 (!data->dropFrameCount_ &&
+			    s->configuration().hints & StreamConfiguration::Hint::MandatoryStream)
+				minIspBuffers = 0;
 		}
 	}
 
@@ -1518,12 +1531,14 @@ 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