From patchwork Wed Nov 1 14:14:19 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Liviu Dudau X-Patchwork-Id: 10036371 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5A2D6602B5 for ; Wed, 1 Nov 2017 14:14:31 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3F18D28BAE for ; Wed, 1 Nov 2017 14:14:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 33E8B28BDD; Wed, 1 Nov 2017 14:14:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 9DD3928BC6 for ; Wed, 1 Nov 2017 14:14:30 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 28AAD6E74D; Wed, 1 Nov 2017 14:14:30 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from cam-smtp0.cambridge.arm.com (fw-tnat.cambridge.arm.com [217.140.96.140]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7D1436E74D for ; Wed, 1 Nov 2017 14:14:28 +0000 (UTC) Received: from e110455-lin.cambridge.arm.com (e110455-lin.cambridge.arm.com [10.2.131.60]) by cam-smtp0.cambridge.arm.com (8.13.8/8.13.8) with ESMTP id vA1EEJsE005409; Wed, 1 Nov 2017 14:14:20 GMT From: Liviu Dudau To: Brian Starkey Subject: [PATCH] drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1 Date: Wed, 1 Nov 2017 14:14:19 +0000 Message-Id: <20171101141419.3180-1-Liviu.Dudau@arm.com> X-Mailer: git-send-email 2.14.3 Cc: David Airlie , Liviu Dudau , LKML , Mali DP Maintainers , DRI-devel , Daniel Vetter X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP drm_gem_cma_prime_import_sg_table() will fail if the number of entries in the sg_table > 1. However, you can have a device that uses an IOMMU engine and can map a discontiguous buffer with multiple entries that have consecutive sg_dma_addresses, effectively making it contiguous. Allow for that scenario by testing the entries in the sg_table for contiguous coverage. Reviewed-by: Brian Starkey Signed-off-by: Liviu Dudau Reviewed-by: Laurent Pinchart --- Hi, This patch is the only change I need in order to be able to use existing IOMMU domain infrastructure with the Mali DP driver. I have tested the patch and I know it works correctly for my setup, but I would like to get some comments on whether I am on the right path or if CMA really wants to see an sg_table with only one entry. Best regards, Liviu drivers/gpu/drm/drm_gem_cma_helper.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index 020e7668dfaba..43b179212052d 100644 --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -482,8 +482,26 @@ drm_gem_cma_prime_import_sg_table(struct drm_device *dev, { struct drm_gem_cma_object *cma_obj; - if (sgt->nents != 1) - return ERR_PTR(-EINVAL); + if (sgt->nents != 1) { + /* check if the entries in the sg_table are contiguous */ + dma_addr_t next_addr = sg_dma_address(sgt->sgl); + struct scatterlist *s; + unsigned int i; + + for_each_sg(sgt->sgl, s, sgt->nents, i) { + /* + * sg_dma_address(s) is only valid for entries + * that have sg_dma_len(s) != 0 + */ + if (!sg_dma_len(s)) + continue; + + if (sg_dma_address(s) != next_addr) + return ERR_PTR(-EINVAL); + + next_addr = sg_dma_address(s) + sg_dma_len(s); + } + } /* Create a CMA GEM buffer. */ cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);