media: platform: fcp: Set appropriate DMA parameters
authorKieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Tue, 7 Apr 2020 15:44:17 +0000 (17:44 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 20 Jun 2020 08:24:15 +0000 (10:24 +0200)
commit6ac24bdb294e6e51d967c38e31fccd2059437b53
tree4bc5c9026d1abd79cd7e742bce871ac5f13f36b7
parentcef66945b620e7e96c71d075c0cc58b2dd30d277
media: platform: fcp: Set appropriate DMA parameters

[ Upstream commit dd844fb8e50b12e65bbdc5746c9876c6735500df ]

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: 7b49235e83b2 ("[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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/media/platform/rcar-fcp.c