From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp-vbr4.xs4all.nl ([194.109.24.24]:1196 "EHLO smtp-vbr4.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752871Ab2JKHUZ (ORCPT ); Thu, 11 Oct 2012 03:20:25 -0400 From: Hans Verkuil To: Mauro Carvalho Chehab Subject: Re: [PATCH] dma-buf: Use EXPORT_SYMBOL Date: Thu, 11 Oct 2012 09:20:12 +0200 Cc: Dave Airlie , Robert Morell , Alan Cox , linaro-mm-sig@lists.linaro.org, rob@ti.com, Sumit Semwal , dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org References: <1349884592-32485-1-git-send-email-rmorell@nvidia.com> <20121010221119.6a623417@redhat.com> In-Reply-To: <20121010221119.6a623417@redhat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201210110920.12560.hverkuil@xs4all.nl> Sender: linux-media-owner@vger.kernel.org List-ID: On Thu October 11 2012 03:11:19 Mauro Carvalho Chehab wrote: > Em Thu, 11 Oct 2012 09:22:34 +1000 > Dave Airlie escreveu: > > > On Thu, Oct 11, 2012 at 4:17 AM, Alan Cox wrote: > > > On Wed, 10 Oct 2012 08:56:32 -0700 > > > Robert Morell wrote: > > > > > >> EXPORT_SYMBOL_GPL is intended to be used for "an internal implementation > > >> issue, and not really an interface". The dma-buf infrastructure is > > >> explicitly intended as an interface between modules/drivers, so it > > >> should use EXPORT_SYMBOL instead. > > > > > > NAK. This needs at the very least the approval of all rights holders for > > > the files concerned and all code exposed by this change. > > > > I think he has that. Maybe he just needs to list them. > > My understanding it that he doesn't, as the dmabuf interface exposes not only > the code written by this driver's author, but other parts of the Kernel. > > Even if someone consider just the dmabuf driver, I participated and actively > contributed, together with other open source developers, during the 3 days > discussions that happened at Linaro's forum where most of dmabuf design was > decided, and participated, reviewed, gave suggestions approved the code, etc > via email. So, even not writing the dmabuf stuff myself, I consider myself as > one of the intelectual authors of the solution. > > Also, as dmabuf will also expose media interfaces, That's new to me. All it does is represent a buffer. It doesn't expose any interfaces, media or otherwise. > my understaning is > that the drivers/media/ authors should also ack with this licensing > (possible) change. I am one of the main contributors there. Alan also has > copyrights there, and at other parts of the Linux Kernel, including the driver's > core, from where all Linux Kernel drivers are derivative work, including this one. > > As Alan well said, many other core Linux Kernel authors very likely share > this point of view. > > So, developers implicitly or explicitly copied in this thread that might be > considering the usage of dmabuf on proprietary drivers should consider > this email as a formal notification of my viewpoint: e. g. that I consider > any attempt of using DMABUF or media core/drivers together with proprietary > Kernelspace code as a possible GPL infringement. As long as dmabuf uses EXPORT_SYMBOL_GPL that is definitely correct. Does your statement also hold if dmabuf would use EXPORT_SYMBOL? (Just asking) BTW, we should consider changing the control framework API to EXPORT_SYMBOL_GPL. The number of contributors to v4l2-ctrls.c is very limited, and I have no problem moving that to GPL. For me dmabuf is the rare exception where I prefer EXPORT_SYMBOL to prevent the worse evil of forcing vendors to create incompatible APIs. It's a sad but true that many GPU drivers are still closed source, particularly in the embedded world for which dmabuf was primarily designed. Regards, Hans