Enabling CONFIG_DMA_API_DEBUG=y and CONFIG_DMA_API_DEBUG_SG=y will
enable extra validation on DMA operations ensuring that the size
restraints are met.
When using the FCP in conjunction with the VSP1/DU, and display frames,
the size of the DMA operations is larger than the default maximum
segment size reported by the DMA core (64K). With the DMA debug enabled,
this produces a warning such as the following:
"DMA-API: rcar-fcp fea27000.fcp: mapping sg segment longer than device
claims to support [len=3145728] [max=65536]"
We have no specific limitation on the segment size which isn't already
handled by the VSP1/DU which actually handles the DMA allcoations and
buffer management, so define a maximum segment size of up to 4GB (a 32
bit mask).
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Fixes: 7b49235e83 ("[media] v4l: Add Renesas R-Car FCP driver")
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
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