From: Gerd Hoffmann <kraxel@redhat.com> To: Helge Deller <deller@gmx.de> Cc: Daniel Vetter <daniel@ffwll.ch>, Linux Fbdev development list <linux-fbdev@vger.kernel.org>, Sven Schnelle <svens@stackframe.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, DRI Development <dri-devel@lists.freedesktop.org>, Javier Martinez Canillas <javierm@redhat.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Thomas Zimmermann <tzimmermann@suse.de>, Linus Torvalds <torvalds@linux-foundation.org> Subject: Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer Date: Tue, 18 Jan 2022 10:16:15 +0100 [thread overview] Message-ID: <20220118091615.3ih5n7vhd6tgmnku@sirius.home.kraxel.org> (raw) In-Reply-To: <ebe9c076-e2a9-0cb7-eb6a-ae71c075975e@gmx.de> On Tue, Jan 18, 2022 at 09:20:43AM +0100, Helge Deller wrote: > On 1/18/22 07:29, Gerd Hoffmann wrote: > >> Please correct me if I'm wrong, but text-console emulation/scrolling on DRM is > >> currently unaccelerated and bound to Truecolour modes only, > > > > Yes. Adding support for formats beside argb8888 to the drm fbcon > > emulation shouldn't be that much of a problem though. > > Really? Assuming a graphic card which runs with only 256 colors framebuffer > is easily supported by DRM, and you can use fbcon without using lots of memcpy()? Driver: programming a fixed color cube palette, then use RGB332. fbcon/fbdev emulation: RGB332 support must be added I think. But both argb888 and rgb565 are supported today, so it should not be hard to find the places where you have to add some code to handle RGB332 too. > > Acceleration is harder. The scroll acceleration had issues nobody > > addressed for years, and on modern hardware it is simply not used, which > > is probably the reason nobody stepped up fixing things and it ended up > > being dropped. > > The DRM layer doesn't use scroll acceleration. > More than 30 other existing fbdev drivers use it. Yes. The world shifted from 2d acceleration to 3d acceleration. Modern hardware simply has no classic blitter any more. Which is a problem when it comes to keeping scroll acceleration alive, it is already a very niche use case and it will only become worse ... > > Bringing it back is much more work than just reverting the commits removing it. > > Reverting those commits have no effect on DRM's usage of fbcon. > But reverting those commits bring back scroll acceleration for all others. > I'm trying to find out which patches did apparently fixed such issues > for the REDRAW case. If you have a pointer it would be helpful. IIRC the code had a bunch of races and syzkaller flagged problems. I didn't follow very closely though. take care, Gerd
WARNING: multiple messages have this Message-ID (diff)
From: Gerd Hoffmann <kraxel@redhat.com> To: Helge Deller <deller@gmx.de> Cc: Linux Fbdev development list <linux-fbdev@vger.kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>, Linus Torvalds <torvalds@linux-foundation.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, DRI Development <dri-devel@lists.freedesktop.org>, Javier Martinez Canillas <javierm@redhat.com>, Geert Uytterhoeven <geert@linux-m68k.org>, Sven Schnelle <svens@stackframe.org> Subject: Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer Date: Tue, 18 Jan 2022 10:16:15 +0100 [thread overview] Message-ID: <20220118091615.3ih5n7vhd6tgmnku@sirius.home.kraxel.org> (raw) In-Reply-To: <ebe9c076-e2a9-0cb7-eb6a-ae71c075975e@gmx.de> On Tue, Jan 18, 2022 at 09:20:43AM +0100, Helge Deller wrote: > On 1/18/22 07:29, Gerd Hoffmann wrote: > >> Please correct me if I'm wrong, but text-console emulation/scrolling on DRM is > >> currently unaccelerated and bound to Truecolour modes only, > > > > Yes. Adding support for formats beside argb8888 to the drm fbcon > > emulation shouldn't be that much of a problem though. > > Really? Assuming a graphic card which runs with only 256 colors framebuffer > is easily supported by DRM, and you can use fbcon without using lots of memcpy()? Driver: programming a fixed color cube palette, then use RGB332. fbcon/fbdev emulation: RGB332 support must be added I think. But both argb888 and rgb565 are supported today, so it should not be hard to find the places where you have to add some code to handle RGB332 too. > > Acceleration is harder. The scroll acceleration had issues nobody > > addressed for years, and on modern hardware it is simply not used, which > > is probably the reason nobody stepped up fixing things and it ended up > > being dropped. > > The DRM layer doesn't use scroll acceleration. > More than 30 other existing fbdev drivers use it. Yes. The world shifted from 2d acceleration to 3d acceleration. Modern hardware simply has no classic blitter any more. Which is a problem when it comes to keeping scroll acceleration alive, it is already a very niche use case and it will only become worse ... > > Bringing it back is much more work than just reverting the commits removing it. > > Reverting those commits have no effect on DRM's usage of fbcon. > But reverting those commits bring back scroll acceleration for all others. > I'm trying to find out which patches did apparently fixed such issues > for the REDRAW case. If you have a pointer it would be helpful. IIRC the code had a bunch of races and syzkaller flagged problems. I didn't follow very closely though. take care, Gerd
next prev parent reply other threads:[~2022-01-18 9:16 UTC|newest] Thread overview: 149+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-01-14 18:11 [PATCH] MAINTAINERS: Add Helge as fbdev maintainer Helge Deller 2022-01-14 18:31 ` Geert Uytterhoeven 2022-01-14 18:31 ` Geert Uytterhoeven 2022-01-17 9:48 ` Daniel Vetter 2022-01-17 9:48 ` Daniel Vetter 2022-01-17 10:02 ` Daniel Vetter 2022-01-17 10:02 ` Daniel Vetter 2022-01-17 10:19 ` Javier Martinez Canillas 2022-01-17 10:19 ` Javier Martinez Canillas 2022-01-17 10:49 ` Jani Nikula 2022-01-17 10:57 ` Helge Deller 2022-01-17 12:15 ` Helge Deller 2022-01-17 12:15 ` Helge Deller 2022-01-17 12:57 ` Gerd Hoffmann 2022-01-17 12:57 ` Gerd Hoffmann 2022-01-17 13:29 ` Geert Uytterhoeven 2022-01-17 13:29 ` Geert Uytterhoeven 2022-01-17 13:51 ` Thomas Zimmermann 2022-01-17 13:51 ` Thomas Zimmermann 2022-01-17 14:10 ` Geert Uytterhoeven 2022-01-17 14:10 ` Geert Uytterhoeven 2022-01-17 14:47 ` Helge Deller 2022-01-17 14:47 ` Helge Deller 2022-01-17 15:03 ` Daniel Vetter 2022-01-17 15:03 ` Daniel Vetter 2022-01-17 20:17 ` Helge Deller 2022-01-17 20:17 ` Helge Deller 2022-01-18 6:29 ` Gerd Hoffmann 2022-01-18 6:29 ` Gerd Hoffmann 2022-01-18 8:10 ` Geert Uytterhoeven 2022-01-18 8:10 ` Geert Uytterhoeven 2022-01-18 11:44 ` Daniel Vetter 2022-01-18 11:44 ` Daniel Vetter 2022-01-18 14:23 ` Thomas Zimmermann 2022-01-18 14:23 ` Thomas Zimmermann 2022-01-18 14:39 ` Simon Ser 2022-01-18 14:39 ` Simon Ser 2022-01-20 12:50 ` Gerd Hoffmann 2022-01-20 12:50 ` Gerd Hoffmann 2022-01-21 8:55 ` Daniel Vetter 2022-01-21 8:55 ` Daniel Vetter 2022-01-24 18:38 ` Geert Uytterhoeven 2022-01-24 18:38 ` Geert Uytterhoeven 2022-01-24 18:50 ` Daniel Vetter 2022-01-24 18:50 ` Daniel Vetter 2022-01-24 19:05 ` Thomas Zimmermann 2022-01-24 19:05 ` Thomas Zimmermann 2022-01-18 8:20 ` Helge Deller 2022-01-18 8:20 ` Helge Deller 2022-01-18 9:16 ` Gerd Hoffmann [this message] 2022-01-18 9:16 ` Gerd Hoffmann 2022-01-18 10:13 ` Helge Deller 2022-01-18 10:13 ` Helge Deller 2022-01-18 10:44 ` Helge Deller 2022-01-18 10:44 ` Helge Deller 2022-01-18 12:48 ` Gerd Hoffmann 2022-01-18 12:48 ` Gerd Hoffmann 2022-01-17 15:05 ` Thomas Zimmermann 2022-01-17 15:05 ` Thomas Zimmermann 2022-01-17 16:05 ` Helge Deller 2022-01-17 16:05 ` Helge Deller 2022-01-17 14:53 ` Thomas Zimmermann 2022-01-17 14:53 ` Thomas Zimmermann 2022-01-18 6:11 ` Gerd Hoffmann 2022-01-18 6:11 ` Gerd Hoffmann 2022-01-18 8:09 ` Helge Deller 2022-01-18 8:09 ` Helge Deller 2022-01-17 15:00 ` Daniel Vetter 2022-01-17 15:00 ` Daniel Vetter 2022-01-17 15:42 ` Helge Deller 2022-01-17 15:42 ` Helge Deller 2022-01-17 15:56 ` Daniel Vetter 2022-01-17 15:56 ` Daniel Vetter 2022-01-17 15:58 ` Thomas Zimmermann 2022-01-17 15:58 ` Thomas Zimmermann 2022-01-17 16:21 ` Helge Deller 2022-01-17 16:21 ` Helge Deller 2022-01-17 16:38 ` Daniel Vetter 2022-01-17 16:38 ` Daniel Vetter 2022-01-17 17:19 ` Helge Deller 2022-01-17 17:19 ` Helge Deller 2022-01-17 19:45 ` Helge Deller 2022-01-17 19:45 ` Helge Deller 2022-01-17 21:55 ` Ilia Mirkin 2022-01-17 21:55 ` Ilia Mirkin 2022-01-18 11:14 ` Daniel Vetter 2022-01-18 11:14 ` Daniel Vetter 2022-01-18 14:14 ` Thomas Zimmermann 2022-01-18 14:14 ` Thomas Zimmermann 2022-01-17 21:40 ` Jani Nikula 2022-01-17 21:40 ` Jani Nikula 2022-01-17 21:44 ` Helge Deller 2022-01-17 21:44 ` Helge Deller 2022-01-18 8:38 ` Jani Nikula 2022-01-18 8:38 ` Jani Nikula 2022-01-18 8:41 ` Geert Uytterhoeven 2022-01-18 8:41 ` Geert Uytterhoeven 2022-01-18 11:41 ` Daniel Vetter 2022-01-18 11:41 ` Daniel Vetter 2022-01-18 12:11 ` Simon Ser 2022-01-18 12:11 ` Simon Ser 2022-01-18 8:54 ` Helge Deller 2022-01-18 8:54 ` Helge Deller 2022-01-18 9:33 ` Javier Martinez Canillas 2022-01-18 9:33 ` Javier Martinez Canillas 2022-01-18 9:45 ` Geert Uytterhoeven 2022-01-18 9:45 ` Geert Uytterhoeven 2022-01-18 11:18 ` Daniel Vetter 2022-01-18 11:18 ` Daniel Vetter 2022-01-18 11:42 ` Helge Deller 2022-01-18 11:42 ` Helge Deller 2022-01-18 8:41 ` Helge Deller 2022-01-18 8:41 ` Helge Deller 2022-01-18 9:12 ` Helge Deller 2022-01-18 9:12 ` Helge Deller 2022-01-17 11:16 ` Thomas Zimmermann 2022-01-17 11:33 ` Helge Deller 2022-01-17 12:13 ` Thomas Zimmermann 2022-01-17 18:47 ` Sven Schnelle 2022-01-18 8:33 ` Pekka Paalanen 2022-01-18 8:33 ` Pekka Paalanen 2022-01-18 9:53 ` Gerd Hoffmann 2022-01-18 9:53 ` Gerd Hoffmann 2022-01-18 11:22 ` Daniel Vetter 2022-01-18 11:22 ` Daniel Vetter 2022-01-18 12:07 ` Gerd Hoffmann 2022-01-18 12:07 ` Gerd Hoffmann 2022-01-19 8:39 ` Pekka Paalanen 2022-01-19 8:39 ` Pekka Paalanen 2022-01-20 9:06 ` Geert Uytterhoeven 2022-01-20 9:06 ` Geert Uytterhoeven 2022-01-20 11:32 ` Daniel Vetter 2022-01-20 11:32 ` Daniel Vetter 2022-01-20 12:13 ` Geert Uytterhoeven 2022-01-20 12:13 ` Geert Uytterhoeven 2022-01-20 12:33 ` Daniel Vetter 2022-01-20 12:33 ` Daniel Vetter 2022-01-20 12:46 ` Geert Uytterhoeven 2022-01-20 12:46 ` Geert Uytterhoeven 2022-01-24 18:50 ` Geert Uytterhoeven 2022-01-24 18:50 ` Geert Uytterhoeven 2022-01-24 19:37 ` Daniel Vetter 2022-01-24 19:37 ` Daniel Vetter 2022-01-20 11:51 ` Gerd Hoffmann 2022-01-20 11:51 ` Gerd Hoffmann 2022-01-18 8:58 ` Michel Dänzer 2022-01-18 10:05 ` Sven Schnelle 2022-01-18 10:05 ` Sven Schnelle 2022-01-18 14:06 ` Thomas Zimmermann
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