From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lucas Stach Subject: Re: [RFC v2 8/8] drm: tegra: Add gr2d device Date: Fri, 30 Nov 2012 08:53:05 +0100 Message-ID: <1354261985.1479.179.camel@tellur> References: <50B60EFF.1050703@nvidia.com> <1354109602.1479.66.camel@tellur> <50B61845.6060102@nvidia.com> <1354111565.1479.73.camel@tellur> <50B6237B.8010808@nvidia.com> <1354115609.1479.91.camel@tellur> <50B63A70.8020107@nvidia.com> <1354128408.1479.137.camel@tellur> <50B71A28.5060807@nvidia.com> <1354180153.1479.162.camel@tellur> <20121129121430.GA3846@avionic-0098.adnet.avionic-design.de> <50B863E4.50700@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <50B863E4.50700@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Terje =?ISO-8859-1?Q?Bergstr=F6m?= Cc: Thierry Reding , Dave Airlie , "linux-tegra@vger.kernel.org" , "dri-devel@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" , Arto Merilainen List-Id: dri-devel@lists.freedesktop.org Am Freitag, den 30.11.2012, 09:44 +0200 schrieb Terje Bergstr=C3=B6m: > On 29.11.2012 14:14, Thierry Reding wrote: > > On Thu, Nov 29, 2012 at 10:09:13AM +0100, Lucas Stach wrote: > >> This way you would also be able to construct different handles (li= ke GEM > >> obj or V4L2 buffers) from the same backing nvhost object. Note tha= t I'm > >> not sure how useful this would be, but it seems like a reasonable = design > >> to me being able to do so. > >=20 > > Wouldn't that be useful for sharing buffers between DRM and V4L2 us= ing > > dma-buf? I'm not very familiar with how exactly importing and expor= ting > > work with dma-buf, so maybe I need to read up some more. >=20 > I would still preserve the dma-buf support, for exactly this purpose. >=20 dma-buf is useful and should be preserved, as some userspace like gstreamer might rely on us being able to import/export dma-buf handles at some time. At the very latest we'll need it if someone wants to run = a UDL device to scanout a buffer rendered to by the internal GPU. What I'm saying is just that with a common allocator we could cut down = a lot on the usage of dma-buf, where not really necessary. Also you might be able to do some optimisations based on the fact that a dma-buf handl= e exported for some V4L2 buffer, which gets imported into DRM to construc= t a GEM object, is the very same nvhost object in the end. Regards, Lucas