From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Date: Wed, 22 Feb 2012 16:24:24 +0000 Subject: Re: Kernel Display and Video API Consolidation mini-summit at ELC 2012 - Notes Message-Id: <20120222162424.GE4872@phenom.ffwll.local> List-Id: References: <201201171126.42675.laurent.pinchart@ideasonboard.com> <1775349.d0yvHiVdjB@avalon> <20120217095554.GA5511@phenom.ffwll.local> <2168398.Pv8ir5xFGf@avalon> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: James Simmons Cc: Laurent Pinchart , Daniel Vetter , Tomasz Stanislawski , linux-fbdev@vger.kernel.org, Sakari Ailus , Pawel Osciak , Magnus Damm , Marcus Lorentzon , dri-devel@lists.freedesktop.org, Alexander Deucher , Rob Clark , linux-media@vger.kernel.org, Marek Szyprowski On Wed, Feb 22, 2012 at 04:03:21PM +0000, James Simmons wrote: > > > > Imo we should ditch this - fb accel doesn't belong into the kernel. Even > > > on hw that still has a blitter for easy 2d accel without a complete 3d > > > state setup necessary, it's not worth it. Chris Wilson from our team once > > > played around with implementing fb accel in the kernel (i915 hw still has > > > a blitter engine in the latest generations). He quickly noticed that to > > > have decent speed, competitive with s/w rendering by the cpu he needs the > > > entire batch and buffer management stuff from userspace. And to really > > > beat the cpu, you need even more magic. > > > > > > If you want fast 2d accel, use something like cairo. > > > > Our conclusion on this is that we should not expose an explicit 2D > > acceleration API at the kernel level. If really needed, hardware 2D > > acceleration could be implemented as a DRM device to handle memory management, > > commands ring setup, synchronization, ... but I'm not even sure if that's > > worth it. I might not have conveyed it well in my notes. > > Fbcon scrolling at be painful at HD or better modes. Fbcon needs 3 > possible accels; copyarea, imageblit, and fillrect. The first two could be > hooked from the TTM layer. Its something I plan to experiment to see if > its worth it. Let's bite into this ;-) I know that fbcon scrolling totally sucks on big screens, but I also think it's a total waste of time to fix this. Imo fbcon has 2 use-cases: - display an OOSP. - allow me to run fsck (or any other desaster-recovery stuff). It can do that quite fine already. Flamy yours, Daniel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48