linux-kernel - [RFC PATCH] drm/komeda: fixing of DMA mapping sg segment warning

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Message-ID: <1553757859-13506-1-git-send-email-lowry.li@arm.com>
Date:   Thu, 28 Mar 2019 07:25:00 +0000
From:   "Lowry Li (Arm Technology China)" <Lowry.Li@....com>
To:     Liviu Dudau <Liviu.Dudau@....com>,
        "james qian wang (Arm Technology China)" <james.qian.wang@....com>,
        "maarten.lankhorst@...ux.intel.com" 
        <maarten.lankhorst@...ux.intel.com>,
        "seanpaul@...omium.org" <seanpaul@...omium.org>,
        "airlied@...ux.ie" <airlied@...ux.ie>,
        Brian Starkey <Brian.Starkey@....com>
CC:     "Julien Yin (Arm Technology China)" <Julien.Yin@....com>,
        "Jonathan Chai (Arm Technology China)" <Jonathan.Chai@....com>,
        Ayan Halder <Ayan.Halder@....com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        nd <nd@....com>
Subject: [RFC PATCH] drm/komeda: fixing of DMA mapping sg segment warning

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.

Signed-off-by: Lowry Li <lowry.li@....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;
 	}
 
+	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 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;
 
 	struct komeda_chip_info chip;
-- 
1.9.1