From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sinan Kaya Subject: [PATCH V3] drm/amdgpu: limit DMA size to PAGE_SIZE for scatter-gather buffers Date: Wed, 11 Apr 2018 18:11:22 -0400 Message-ID: <1523484684-10426-1-git-send-email-okaya@codeaurora.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: amd-gfx@lists.freedesktop.org, sulrich@codeaurora.org, timur@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , Alex Deucher , =?UTF-8?q?Christian=20K=C3=B6nig?= , "David (ChunMing) Zhou" , David Airlie , Monk Liu , Harry Wentland , Pixel Ding , Horace Chen , "open list:DRM DRIVERS" , open list List-Id: linux-arm-msm@vger.kernel.org Code is expecing to observe the same number of buffers returned from dma_map_sg() function compared to sg_alloc_table_from_pages(). This doesn't hold true universally especially for systems with IOMMU. The hardware actually needs the dma_address on a page by page basis. Joining multiple consecutive pages into one entry is just additional overhead which we don't need. Signed-off-by: Sinan Kaya --- drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c index af1b879..91abe1a 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c @@ -1948,6 +1948,9 @@ int amdgpu_device_init(struct amdgpu_device *adev, /* init the mode config */ drm_mode_config_init(adev->ddev); + /* limit scatter-gather buffer size to PAGE_SIZE */ + dma_set_max_seg_size(adev->dev, PAGE_SIZE); + r = amdgpu_device_ip_init(adev); if (r) { /* failed in exclusive mode due to timeout */ -- 2.7.4