From: Thomas Zimmermann <tzimmermann@suse.de>
To: Helge Deller <deller@gmx.de>, Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>,
Daniel Vetter <daniel@ffwll.ch>,
Linus Torvalds <torvalds@linux-foundation.org>,
"airlied@gmail.com" <airlied@gmail.com>,
Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
Javier Martinez Canillas <javierm@redhat.com>
Subject: Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer
Date: Mon, 17 Jan 2022 16:05:39 +0100 [thread overview]
Message-ID: <faa46e76-d38c-f436-d005-ce69915033fb@suse.de> (raw)
In-Reply-To: <57d276d3-aa12-fa40-6f90-dc19ef393679@gmx.de>
[-- Attachment #1.1: Type: text/plain, Size: 2359 bytes --]
Hi
Am 17.01.22 um 15:47 schrieb Helge Deller:
> On 1/17/22 15:10, Geert Uytterhoeven wrote:
> [...]
>> Using an XRGB32 intermediate would kill the user experience on old
>> machines, due to both increased memory usage and copy overhead.
>>
>>> Personally, I'd much appreciate if userspace would support more of the
>>> native formats and not rely on XRGB32.
>>
>> Supporting monochrome, 16 colors, and 256 colors would be nice.
>
> From this conversation it seems DRM completely lacks backwards compatibility,
> including a missing 2D bitblt copy.
> Isn't that all what's needed and then migrating existing drivers would
> be easy ?
What exactly do you mean by 'backwards compatibility'? The driver API is
different, of course. My conversion helpers can provide a starting point
to move fbdev code into DRM drivers.
For fbdev 2d-bitblt ioctls, you can add them to DRM drivers and set up
DRM's fbdev emulation accordingly. Some DRM drivers do/did this. To my
knowledge, so far there's not been a use case where that provides a
benefit over simple memcpy. For fast 2d blitting from userspace, you
should read Daniel's comment at [1]. tl;dr: a generic solution is
non-trivial.
Best regards
Thomas
[1] https://blog.ffwll.ch/2018/08/no-2d-in-drm.html
>
> Helge
>
>
>>>> This not only to support "old" hardware, but also modern small OLED
>>>> and e-ink displays.
>>>
>>> There's a DRM driver for Repaper e-Ink displays. So it seems doable at
>>> least.
>>
>> Which uses an DRM_FORMAT_XRGB8888 intermediate, and
>> drm_fb_xrgb8888_to_gray8() and repaper_gray8_to_mono_reversed()
>> to convert from truecolor to monochrome. I guess that would work,
>> as this is a slow e-ink display. Have fun as a text console ;-)
>>
>> Gr{oetje,eeting}s,
>>
>> Geert
>>
>> --
>> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>>
>> In personal conversations with technical people, I call myself a hacker. But
>> when I'm talking to journalists I just say "programmer" or something like that.
>> -- Linus Torvalds
>>
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev
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next prev parent reply other threads:[~2022-01-17 15:05 UTC|newest]
Thread overview: 79+ 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
2022-01-17 9:48 ` Daniel Vetter
2022-01-17 10:02 ` Daniel Vetter
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 12:57 ` Gerd Hoffmann
2022-01-17 13:29 ` Geert Uytterhoeven
2022-01-17 13:51 ` Thomas Zimmermann
2022-01-17 14:10 ` Geert Uytterhoeven
2022-01-17 14:47 ` Helge Deller
2022-01-17 15:03 ` Daniel Vetter
2022-01-17 20:17 ` Helge Deller
2022-01-18 6:29 ` Gerd Hoffmann
2022-01-18 8:10 ` Geert Uytterhoeven
2022-01-18 11:44 ` Daniel Vetter
2022-01-18 14:23 ` Thomas Zimmermann
2022-01-18 14:39 ` Simon Ser
2022-01-20 12:50 ` Gerd Hoffmann
2022-01-21 8:55 ` Daniel Vetter
2022-01-24 18:38 ` Geert Uytterhoeven
2022-01-24 18:50 ` Daniel Vetter
2022-01-24 19:05 ` Thomas Zimmermann
2022-01-18 8:20 ` Helge Deller
2022-01-18 9:16 ` Gerd Hoffmann
2022-01-18 10:13 ` Helge Deller
2022-01-18 10:44 ` Helge Deller
2022-01-18 12:48 ` Gerd Hoffmann
2022-01-17 15:05 ` Thomas Zimmermann [this message]
2022-01-17 16:05 ` Helge Deller
2022-01-17 14:53 ` Thomas Zimmermann
2022-01-18 6:11 ` Gerd Hoffmann
2022-01-18 8:09 ` Helge Deller
2022-01-17 15:00 ` Daniel Vetter
2022-01-17 15:42 ` Helge Deller
2022-01-17 15:56 ` Daniel Vetter
2022-01-17 15:58 ` Thomas Zimmermann
2022-01-17 16:21 ` Helge Deller
2022-01-17 16:38 ` Daniel Vetter
2022-01-17 17:19 ` Helge Deller
2022-01-17 19:45 ` Helge Deller
2022-01-17 21:55 ` Ilia Mirkin
2022-01-18 11:14 ` Daniel Vetter
2022-01-18 14:14 ` Thomas Zimmermann
2022-01-17 21:40 ` Jani Nikula
2022-01-17 21:44 ` Helge Deller
2022-01-18 8:38 ` Jani Nikula
2022-01-18 8:41 ` Geert Uytterhoeven
2022-01-18 11:41 ` Daniel Vetter
2022-01-18 12:11 ` Simon Ser
2022-01-18 8:54 ` Helge Deller
2022-01-18 9:33 ` Javier Martinez Canillas
2022-01-18 9:45 ` Geert Uytterhoeven
2022-01-18 11:18 ` Daniel Vetter
2022-01-18 11:42 ` Helge Deller
2022-01-18 8:41 ` 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 9:53 ` Gerd Hoffmann
2022-01-18 11:22 ` Daniel Vetter
2022-01-18 12:07 ` Gerd Hoffmann
2022-01-19 8:39 ` Pekka Paalanen
2022-01-20 9:06 ` Geert Uytterhoeven
2022-01-20 11:32 ` Daniel Vetter
2022-01-20 12:13 ` Geert Uytterhoeven
2022-01-20 12:33 ` Daniel Vetter
2022-01-20 12:46 ` Geert Uytterhoeven
2022-01-24 18:50 ` Geert Uytterhoeven
2022-01-24 19:37 ` Daniel Vetter
2022-01-20 11:51 ` Gerd Hoffmann
2022-01-18 8:58 ` Michel Dänzer
2022-01-18 10:05 ` Sven Schnelle
2022-01-18 14:06 ` Thomas Zimmermann
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