From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756369AbcE0VG3 (ORCPT ); Fri, 27 May 2016 17:06:29 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:37737 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751575AbcE0VG2 (ORCPT ); Fri, 27 May 2016 17:06:28 -0400 Date: Fri, 27 May 2016 18:06:19 -0300 From: Gustavo Padovan To: Dave Jones , Linux Kernel Mailing List , Daniel Vetter , Greg Kroah-Hartman Subject: Re: dma-buf/sync_file: de-stage sync_file Message-ID: <20160527210619.GE15155@joana> References: <20160521053153.14B99661B7C@gitolite.kernel.org> <20160526024209.GA2840@codemonkey.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160526024209.GA2840@codemonkey.org.uk> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2016-05-25 Dave Jones : > On Sat, May 21, 2016 at 05:31:53AM +0000, Linux Kernel wrote: > > > dma-buf/sync_file: de-stage sync_file > > > > sync_file is useful to connect one or more fences to the file. The file is > > used by userspace to track fences between drivers that share DMA bufs. > > > > Signed-off-by: Gustavo Padovan > > Reviewed-by: Daniel Vetter > > Signed-off-by: Greg Kroah-Hartman > > ... > > > +config SYNC_FILE > > + bool "sync_file support for fences" > > + default n > > + select ANON_INODES > > + select DMA_SHARED_BUFFER > > + ---help--- > > + This option enables the fence framework synchronization to export > > + sync_files to userspace that can represent one or more fences. > > For such a generic sounding CONFIG_ item, this is one of the more obtuse descriptions > in a kconfig we've had in a while, and the commit message doesn't give any more > clues as to why anyone might want to enable this. > > I'm guessing this is some graphics thing given that Daniel reviewed it. > From skimming the other commits, it seems to be some Android thing ? > Are there depends missing perhaps that might make this more obvious ? You are right, only a few people understand this in the way I wrote. I definitelly reword this. It is android framework to help userspace with explict synchronization. DRM will require this, but the patches for that did not land yet. Gustavo