[PATCH AUTOSEL 4.9 21/50] media: platform: fcp: Set appropriate DMA parameters

Sasha Levin
2020-06-08T23:33:32Z

From: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>

[ 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 | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/media/platform/rcar-fcp.c b/drivers/media/platform/rcar-fcp.c
index f3a3f31cdfa9..8e9c3bd36d03 100644
--- a/drivers/media/platform/rcar-fcp.c
+++ b/drivers/media/platform/rcar-fcp.c
@@ -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);
--
2.25.1