From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C335C47255 for ; Mon, 11 May 2020 15:51:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7EBE4206DB for ; Mon, 11 May 2020 15:51:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730793AbgEKPv1 (ORCPT ); Mon, 11 May 2020 11:51:27 -0400 Received: from foss.arm.com ([217.140.110.172]:35120 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729556AbgEKPvZ (ORCPT ); Mon, 11 May 2020 11:51:25 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B9ED230E; Mon, 11 May 2020 08:51:24 -0700 (PDT) Received: from [192.168.1.84] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 19DA63F305; Mon, 11 May 2020 08:51:22 -0700 (PDT) Subject: Re: [PATCH v3 10/25] drm: panfrost: fix common struct sg_table related issues To: Marek Szyprowski , dri-devel@lists.freedesktop.org, iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org Cc: Rob Herring , Tomeu Vizoso , Bartlomiej Zolnierkiewicz , David Airlie , Daniel Vetter , Robin Murphy , Christoph Hellwig , linux-arm-kernel@lists.infradead.org References: <20200505083926.28503-1-m.szyprowski@samsung.com> <20200505084614.30424-1-m.szyprowski@samsung.com> <20200505084614.30424-10-m.szyprowski@samsung.com> From: Steven Price Message-ID: Date: Mon, 11 May 2020 16:51:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200505084614.30424-10-m.szyprowski@samsung.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/05/2020 09:45, Marek Szyprowski wrote: > The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the > numer of the created entries in the DMA address space. However the > subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be > called with the original number of the entries passed to dma_map_sg. The > sg_table->nents in turn holds the result of the dma_map_sg call as stated > in include/linux/scatterlist.h. A common mistake was to ignore a result > of the dma_map_sg function and don't use the sg_table->orig_nents at all. > > To avoid such issues, lets use common dma-mapping wrappers operating > directly on the struct sg_table objects and adjust references to the > nents and orig_nents respectively. > > Signed-off-by: Marek Szyprowski The change looks good to me: Reviewed-by: Steven Price Although I would have appreciated the commit message being modified to match the specifics of Panfrost - the return of dma_mpa_sg() wasn't being ignored, but the use of orig_nents/nents was indeed wrong. Steve > --- > For more information, see '[PATCH v3 00/25] DRM: fix struct sg_table nents > vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/5/187 > --- > drivers/gpu/drm/panfrost/panfrost_gem.c | 4 ++-- > drivers/gpu/drm/panfrost/panfrost_mmu.c | 5 ++--- > 2 files changed, 4 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c > index 17b654e..95d7e80 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_gem.c > +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c > @@ -41,8 +41,8 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj) > > for (i = 0; i < n_sgt; i++) { > if (bo->sgts[i].sgl) { > - dma_unmap_sg(pfdev->dev, bo->sgts[i].sgl, > - bo->sgts[i].nents, DMA_BIDIRECTIONAL); > + dma_unmap_sgtable(pfdev->dev, &bo->sgts[i], > + DMA_BIDIRECTIONAL); > sg_free_table(&bo->sgts[i]); > } > } > diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c > index ed28aeb..9926111 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c > +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c > @@ -517,10 +517,9 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as, > if (ret) > goto err_pages; > > - if (!dma_map_sg(pfdev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL)) { > - ret = -EINVAL; > + ret = dma_map_sgtable(pfdev->dev, sgt, DMA_BIDIRECTIONAL); > + if (ret) > goto err_map; > - } > > mmu_map_sg(pfdev, bomapping->mmu, addr, > IOMMU_WRITE | IOMMU_READ | IOMMU_NOEXEC, sgt); >