[libcamera-devel,v2] libcamera: raspberrypi: Document vc_sm_cma pointer sharing with IPA
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Message ID 20200630124307.83848-1-niklas.soderlund@ragnatech.se
State Accepted
Commit 8e137b08194ea73c63832750af5ad2930688aa8a
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  • [libcamera-devel,v2] libcamera: raspberrypi: Document vc_sm_cma pointer sharing with IPA
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Commit Message

Niklas Söderlund June 30, 2020, 12:43 p.m. UTC 
Sharing a pointer with the IPA is fragile as it will not work with all
IPC mechanisms. Document that it's a temporary workaround that should be
reworked.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
* Changes since v1
- Make comment less alarmist.
---
 src/libcamera/pipeline/raspberrypi/raspberrypi.cpp | 5 +++++
 1 file changed, 5 insertions(+)

Patch
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diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index 9d887b706c3f9670..f4966f8628eedbdd 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -1014,6 +1014,11 @@  int PipelineHandlerRPi::configureIPA(Camera *camera)
 		/*
 		 * The vcsm allocation will always be in the memory region
 		 * < 32-bits to allow Videocore to access the memory.
+		 *
+		 * \todo Sending a pointer to the IPA is a workaround for
+		 * vc_sm_cma not yet supporting dmabuf. This will not work with
+		 * IPA module isolation and should be reworked when vc_sma_cma
+		 * will permit.
 		 */
 		IPAOperationData op;
 		op.operation = RPI_IPA_EVENT_LS_TABLE_ALLOCATION;