From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757288AbdKOOZD (ORCPT ); Wed, 15 Nov 2017 09:25:03 -0500 Received: from smtp.domeneshop.no ([194.63.252.55]:46865 "EHLO smtp.domeneshop.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757228AbdKOOYy (ORCPT ); Wed, 15 Nov 2017 09:24:54 -0500 Subject: Re: [PATCH v2] drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1 To: Liviu Dudau , Laurent Pinchart Cc: David Airlie , intel-gfx@lists.freedesktop.org, LKML , DRI-devel , Mali DP Maintainers , Daniel Vetter References: <2213365.Z1vsgl9bDt@avalon> <20171110133310.1225-1-Liviu.Dudau@arm.com> <26071297.cMn4QuKrlS@avalon> <20171115130450.GA31361@e110455-lin.cambridge.arm.com> From: =?UTF-8?Q?Noralf_Tr=c3=b8nnes?= Message-ID: <14804f07-697f-cfc9-d325-6eb3888b04e3@tronnes.org> Date: Wed, 15 Nov 2017 15:24:41 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171115130450.GA31361@e110455-lin.cambridge.arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Den 15.11.2017 14.04, skrev Liviu Dudau: > Hi, > > On Sat, Nov 11, 2017 at 02:47:35PM +0200, Laurent Pinchart wrote: >> Hi Liviu, >> >> Thank you for the patch. >> >> On Friday, 10 November 2017 15:33:10 EET Liviu Dudau wrote: >>> 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: Laurent Pinchart >>> Signed-off-by: Liviu Dudau >>> --- >>> >>> Laurent, >>> >>> Thanks for the review! I would like to ask for one more favour: if you >>> are OK with this version, can you pull this patch through the drm-misc tree? >> I could, but I'd first need to set dim up, and I'm currently abroad with a bad >> internet connection and a big deadline for the middle of next week (I know, >> lots of excuses), so it's not very convenient for me at this time. > Any other drm-misc maintainers feeling helpful and willing to take this > patch in? Sure, I can do it this evening. Noralf. > Otherwise I can send it through the mali-dp tree if no one > objects. > > Best regards, > Liviu > >>> drivers/gpu/drm/drm_gem_cma_helper.c | 22 ++++++++++++++++++++-- >>> include/drm/drm_gem_cma_helper.h | 4 +++- >>> 2 files changed, 23 insertions(+), 3 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); >>> diff --git a/include/drm/drm_gem_cma_helper.h >>> b/include/drm/drm_gem_cma_helper.h index 58a739bf15f1f..214aa85adc8d5 >>> 100644 >>> --- a/include/drm/drm_gem_cma_helper.h >>> +++ b/include/drm/drm_gem_cma_helper.h >>> @@ -8,7 +8,9 @@ >>> * struct drm_gem_cma_object - GEM object backed by CMA memory allocations >>> * @base: base GEM object >>> * @paddr: physical address of the backing memory >>> - * @sgt: scatter/gather table for imported PRIME buffers >>> + * @sgt: scatter/gather table for imported PRIME buffers. The table can >>> have + * more than one entry but they are guaranteed to have >>> contiguous + * DMA addresses. >>> * @vaddr: kernel virtual address of the backing memory >>> */ >>> struct drm_gem_cma_object { >> -- >> Regards, >> >> Laurent Pinchart >>