Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267860AbUIKIoG (ORCPT ); Sat, 11 Sep 2004 04:44:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267961AbUIKIoG (ORCPT ); Sat, 11 Sep 2004 04:44:06 -0400 Received: from colossus.systems.pipex.net ([62.241.160.73]:57023 "EHLO colossus.systems.pipex.net") by vger.kernel.org with ESMTP id S267860AbUIKIn6 (ORCPT ); Sat, 11 Sep 2004 04:43:58 -0400 Message-ID: <4142BACC.4080708@tungstengraphics.com> Date: Sat, 11 Sep 2004 09:43:56 +0100 From: Keith Whitwell User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8a3) Gecko/20040817 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Vladimir Dergachev Cc: Alan Cox , Dave Airlie , Jon Smirl , =?ISO-8859-1?Q?Felix_K=FChling?= , DRI Devel , lkml , Linus Torvalds Subject: Re: radeon-pre-2 References: <9e47339104090919015b5b5a4d@mail.gmail.com> <20040910153135.4310c13a.felix@trabant> <9e47339104091008115b821912@mail.gmail.com> <1094829278.17801.18.camel@localhost.localdomain> <9e4733910409100937126dc0e7@mail.gmail.com> <1094832031.17883.1.camel@localhost.localdomain> <9e47339104091010221f03ec06@mail.gmail.com> <1094835846.17932.11.camel@localhost.localdomain> <9e47339104091011402e8341d0@mail.gmail.com> <1094853588.18235.12.camel@localhost.localdomain> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2233 Lines: 55 Vladimir Dergachev wrote: > > Alan, > I would like to disagree with you. > > On Fri, 10 Sep 2004, Alan Cox wrote: > >> On Gwe, 2004-09-10 at 23:19, Dave Airlie wrote: >> >>> If the kernel developers can address this point I would be most >>> interested, in fact I don't want to hear any more about sharing lowlevel >>> VGA device drivers until someone addresses why it is acceptable to have >>> two separate driver driving the same hardware for video and not for >>> anything else.. (remembering graphics cards are not-multifunction >>> cards - >>> like Christoph used as an example before - 2d/3d are not separate >>> functions...)... >> >> >> We've addressed this before. Zillions of drivers provide multiple >> functions to multiple higher level subsystems. They don't all have to >> be compiled together to make it work. >> >> 2D and 3D _are_ to most intents and purposes different functions. They >> are as different as IDE CD and IDE disk if not more so. > > > Functions - yes, but they become such only at a higher level. 3d for > example does not really exist in kernel in any form. > > I would like to see unified fb (or the hardware-specific part of fb) and > drm for one simple reason that I think you mentioned: > > One driver per device. I.e. one driver per *physical* device. > > Lastly, one point that you appear to have missed: DRM does DMA transfers > (among everything else). FB sets video modes - i.e. messes with PLL. > The problem is that there are configurations where messing with PLL > while a DMA trasfer is active will lock up PCI (or AGP) bus hard. > > For example, a video decoder can be clocked off pixel clock for video > pass through mode. If we trasfer video data to main RAM at the same time > and > FB gets a command instructing it to change resolution there would be a > hard lockup. I can see this being the case, but why can't fb just using existing drm interfaces to achieve device quiescence before touching the PLL's? Keith - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/