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Commit 6ac24bdb authored by Kieran Bingham's avatar Kieran Bingham Committed by Greg Kroah-Hartman
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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: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Fixes: 7b49235e ("[media] v4l: Add Renesas R-Car FCP driver")
Signed-off-by: default avatarKieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Tested-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent cef66945

drivers/media/platform/rcar-fcp.c

+5 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
 */



#include <linux/device.h>

#include <linux/dma-mapping.h>

#include <linux/list.h>

#include <linux/module.h>

#include <linux/mutex.h>
@@ -24,6 +25,7 @@ 
struct rcar_fcp_device {

	struct list_head list;

	struct device *dev;

	struct device_dma_parameters dma_parms;

};



static LIST_HEAD(fcp_devices);
@@ -140,6 +142,9 @@ static int rcar_fcp_probe(struct platform_device *pdev) 


	fcp->dev = &pdev->dev;



	fcp->dev->dma_parms = &fcp->dma_parms;

	dma_set_max_seg_size(fcp->dev, DMA_BIT_MASK(32));



	pm_runtime_enable(&pdev->dev);



	mutex_lock(&fcp_lock);