From dd844fb8e50b12e65bbdc5746c9876c6735500df Mon Sep 17 00:00:00 2001
From: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Date: Tue, 7 Apr 2020 17:44:17 +0200
Subject: [PATCH] media: platform: fcp: Set appropriate DMA parameters
Git-commit: dd844fb8e50b12e65bbdc5746c9876c6735500df
Patch-mainline: v5.8-rc1
References: bsc#1051510

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/media/platform/rcar-fcp.c |    5 +++++
 1 file changed, 5 insertions(+)

--- 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 platfor
 
 	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);