From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751918AbeDJSZP (ORCPT ); Tue, 10 Apr 2018 14:25:15 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:53542 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751504AbeDJSZN (ORCPT ); Tue, 10 Apr 2018 14:25:13 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org CF3BA60274 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org From: Sinan Kaya To: amd-gfx@lists.freedesktop.org, timur@codeaurora.org, sulrich@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 , =?UTF-8?q?Michel=20D=C3=A4nzer?= , Tom St Denis , Felix Kuehling , Roger He , Monk Liu , Harish Kasiviswanathan , dri-devel@lists.freedesktop.org (open list:DRM DRIVERS), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] drm/amdgpu: limit DMA size to PAGE_SIZE for scatter-gather buffers Date: Tue, 10 Apr 2018 14:25:03 -0400 Message-Id: <1523384705-3976-1-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@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. IOMMU driver tries to combine buffers into a single DMA address as much as it can. The right thing is to tell the DMA layer how much combining IOMMU can do. Signed-off-by: Sinan Kaya --- drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c index e4bb435..02465cd 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c @@ -787,6 +787,8 @@ static int amdgpu_ttm_tt_pin_userptr(struct ttm_tt *ttm) enum dma_data_direction direction = write ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE; + dma_set_max_seg_size(adev->dev, PAGE_SIZE); + r = sg_alloc_table_from_pages(ttm->sg, ttm->pages, ttm->num_pages, 0, ttm->num_pages << PAGE_SHIFT, GFP_KERNEL); -- 2.7.4