[RFC PATCH v2] drm/komeda: fixing of DMA mapping sg segment warning

[Lowry Li (Arm Technology China)]

Fixing the DMA mapping sg segment warning, which shows "DMA-API: mapping
sg segment longer than device claims to support [len=921600] [max=65536]".
Fixed by setting the max segment size at Komeda driver.

This patch depends on:
- https://patchwork.freedesktop.org/series/54448/
- https://patchwork.freedesktop.org/series/54449/
- https://patchwork.freedesktop.org/series/54450/
- https://patchwork.freedesktop.org/series/58976/

Changes since v1:
- Adds member description
- Adds patch denpendency in the comment

Signed-off-by: Lowry Li (Arm Technology China) <lowry.li at arm.com>
---
 drivers/gpu/drm/arm/display/komeda/komeda_dev.c | 4 ++++
 drivers/gpu/drm/arm/display/komeda/komeda_dev.h | 2 ++
 2 files changed, 6 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;
 	}
 
+	dev->dma_parms = &mdev->dma_parms;
+	dma_set_max_seg_size(dev, DMA_BIT_MASK(32));
+
 	err = 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 29e03c4..83ace71 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_dev.h
@@ -149,6 +149,8 @@ struct komeda_dev {
 	struct device *dev;
 	/** @reg_base: the base address of komeda io space */
 	u32 __iomem   *reg_base;
+	/** @dma_parms: the dma parameters of komeda */
+	struct device_dma_parameters dma_parms;
 
 	/** @chip: the basic chip information */
 	struct komeda_chip_info chip;
-- 
1.9.1