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 2988031d285d..0047d144c932 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); @@ -139,6 +141,9 @@ 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);