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Subject: [RFC PATCH] drm/komeda: fixing of DMA mapping sg segment warning
Thread-Topic: [RFC PATCH] drm/komeda: fixing of DMA mapping sg segment warning
Thread-Index: AQHU5Tdaj2sOzmoqEEaVRCerOJix/w==
Date:   Thu, 28 Mar 2019 07:25:00 +0000
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Fixing the DMA mapping sg segment warning, which shows "DMA-API: mapping
sg segment longer than device claims to support [len=3D921600] [max=3D65536=
]".
Fixed by setting the max segment size at Komeda driver.

Signed-off-by: Lowry Li <lowry.li@arm.com>
---
 drivers/gpu/drm/arm/display/komeda/komeda_dev.c | 4 ++++
 drivers/gpu/drm/arm/display/komeda/komeda_dev.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_dev.c b/drivers/gpu/=
drm/arm/display/komeda/komeda_dev.c
index 7f25e6a..b4902ae 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_dev.c
@@ -8,6 +8,7 @@
 #include <linux/of_device.h>
 #include <linux/of_graph.h>
 #include <linux/platform_device.h>
+#include <linux/dma-iommu.h>
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -245,6 +246,9 @@ struct komeda_dev *komeda_dev_create(struct device *dev=
)
 		goto err_cleanup;
 	}
=20
+	dev->dma_parms =3D &mdev->dma_parms;
+	dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
+
 	err =3D sysfs_create_group(&dev->kobj, &komeda_sysfs_attr_group);
 	if (err) {
 		DRM_ERROR("create sysfs group failed.\n");
diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_dev.h b/drivers/gpu/=
drm/arm/display/komeda/komeda_dev.h
index 0c3e32b..d8cfa92 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
@@ -146,6 +146,7 @@ enum {
  */
 struct komeda_dev {
 	struct device *dev;
+	struct device_dma_parameters dma_parms;
 	u32 __iomem   *reg_base;
=20
 	struct komeda_chip_info chip;
--=20
1.9.1