Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753676AbcLIIgH (ORCPT ); Fri, 9 Dec 2016 03:36:07 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:36152 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753008AbcLIIeg (ORCPT ); Fri, 9 Dec 2016 03:34:36 -0500 Date: Fri, 9 Dec 2016 09:34:42 +0100 From: Daniel Vetter To: Benjamin Herrenschmidt Cc: Daniel Vetter , Geert Uytterhoeven , Thomas Petazzoni , Tomi Valkeinen , Greg Kroah-Hartman , Noralf =?iso-8859-1?Q?Tr=F8nnes?= , Sudip Mukherjee , Teddy Wang , Arnaud Patard , DRI Development , Linux Fbdev development list , "linux-kernel@vger.kernel.org" Subject: Re: [RFC PATCH 0/3] staging: remove fbdev drivers Message-ID: <20161209083442.peoriqsto2llvl2t@phenom.ffwll.local> Mail-Followup-To: Benjamin Herrenschmidt , Geert Uytterhoeven , Thomas Petazzoni , Tomi Valkeinen , Greg Kroah-Hartman , Noralf =?iso-8859-1?Q?Tr=F8nnes?= , Sudip Mukherjee , Teddy Wang , Arnaud Patard , DRI Development , Linux Fbdev development list , "linux-kernel@vger.kernel.org" References: <1481158879.26959.41.camel@kernel.crashing.org> <20161208101005.6ufl3d4qvwprosju@phenom.ffwll.local> <20161208140210.rfyjf2265flsfpfj@phenom.ffwll.local> <20161208153735.74d7d350@free-electrons.com> <20161208152134.wnv4j4i6m5xpoycp@phenom.ffwll.local> <1481232877.26959.52.camel@kernel.crashing.org> <1481234249.26959.55.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1481234249.26959.55.camel@kernel.crashing.org> X-Operating-System: Linux phenom 4.8.0-1-amd64 User-Agent: NeoMutt/20161104 (1.7.1) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1703 Lines: 36 On Fri, Dec 09, 2016 at 08:57:29AM +1100, Benjamin Herrenschmidt wrote: > On Fri, 2016-12-09 at 08:34 +1100, Benjamin Herrenschmidt wrote: > > As I mentioned earlier, probably 1 or 2 years ago, Dave made the > > argument that shadowing through memory was necessary and precluded 2D > > accel, though I don't fully remember the root of the argument. If that > > is indeed not the case, then my main objection is lifted. > > Things seem to change quickly as Daniel pointed out. > > So ast and cirrus seem to still use a manual dirty tracking and > shadowing (though I'm not sure why), but the infrastructure for > that has moved from the drivers to the helpers. > > bochs (qemu) doesn't seem to anymore from what I can see as it > doesn't have a ->dirty callback. Yeah if you have discrete vram then your dumb display driver isn't all that pretty. We essentially just have the few drivers Dave hacked up to be able to boot some servers. And there's definitely lots of room for more shared code for those, and also some better infrastructure and helpers to share more cod and make them better. The massive pile of dumb framebuffers we all merged over the past 2 years all use system/dma memory for scanout, and for those we have the very nice cma helpers that take care of everything for you. So it is possible, only reason vram dumb buffers look worse is that there's only 3 and no one cares about them, vs about 20 and a very active community of contributors (also for core drm improvements) for the other case. Althought the MXSFB driver that just landed does use ttm and vram, so maybe that's now improving too. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch