From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Hellstrom Subject: Re: [RFC] dma-buf: Implement test module Date: Sat, 14 Dec 2013 13:47:41 +0100 Message-ID: <52AC536D.70901@shipmail.org> References: <1386858989-1487-1-git-send-email-treding@nvidia.com> <52AA0FC4.3090606@vmware.com> <20131214123709.GE17467@mithrandir> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.bahnhof.se (mx2.bahnhof.se [213.80.101.12]) by gabe.freedesktop.org (Postfix) with ESMTP id 6FD35FAE03 for ; Sat, 14 Dec 2013 04:48:01 -0800 (PST) In-Reply-To: <20131214123709.GE17467@mithrandir> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org To: Thierry Reding Cc: Thomas Hellstrom , Greg Kroah-Hartman , Linux Kernel Mailing List , dri-devel , "linaro-mm-sig@lists.linaro.org" List-Id: dri-devel@lists.freedesktop.org On 12/14/2013 01:37 PM, Thierry Reding wrote: > On Thu, Dec 12, 2013 at 11:30:23PM +0100, Daniel Vetter wrote: >> On Thu, Dec 12, 2013 at 8:34 PM, Thomas Hellstrom wrote: >>> On 12/12/2013 03:36 PM, Thierry Reding wrote: >>>> This is a simple test module that can be used to allocate, export and >>>> delete DMA-BUF objects. It can be used to test DMA-BUF sharing in >>>> systems that lack a real second driver. >>>> >>>> >>> Looks nice. I wonder whether this could be extended to create a "streaming" >>> dma-buf from a user space mapping. That could be used as a generic way to >>> implement streaming (user) buffer objects, rather than to add explicit >>> support for those in, for example, TTM. >> Atm there's no way to get gpus to unbind their dma-buf mappings, so >> their essentially pinned forever from first use on. > Shouldn't this work by simply calling the GEM_CLOSE IOCTL on the handle > returned by drmPrimeFDToHandle()? I mean that should drop the last > reference on the GEM object and cause it to be cleaned up (which should > include detaching the DMA-BUF). Actually, while the GEM prime implementation appears to pin an exported dma-buf on first attach, from the dma-buf documentation it seems sufficient to pin it on map or cpu access. But what I assume Daniel is referring to is that there is no way for exporters to tell importers to force unmap() the dma-buf, so that it can be unpinned? Daniel, maybe you could elaborate a bit on this? Thomas > > Thierry > > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel