Messages in this thread | | | Date | Mon, 17 Jan 2022 16:05:39 +0100 | Subject | Re: [PATCH] MAINTAINERS: Add Helge as fbdev maintainer | From | Thomas Zimmermann <> |
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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 [unhandled content-type:application/pgp-signature] | |