Re: [PATCH] fbdev: udl: Make CONFIG_FB_DEVICE optional

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Hi

Am 30.10.24 um 10:30 schrieb Helge Deller:


I'm happy to get rid of the fbdev drivers, but for that DRM really needs to allow some sort of native fillrect, copyarea and imageblt operations so that we can get performance back on the old cards when implementing them
as DRM driver.

This is unrelated to udl.

No, it's not.
The udl fbdev driver implements those functions (like the other fbdev drivers) and as such fbcon on top of udl is accelerated, while fbcon on drm drivers
is unaccelerated.

Udlfb uses the regular software implementations to draw into its shadow buffer. It then schedules an update to copy the update over USB to the adapter's internal framebuffer memory. [1] Udl uses exactly the same code pattern and most of the involved helpers. [2]

[1] https://elixir.bootlin.com/linux/v6.11.5/source/drivers/video/fbdev/udlfb.c#L1145 [2] https://elixir.bootlin.com/linux/v6.11.5/source/drivers/gpu/drm/drm_fbdev_shmem.c#L39

Best regards
Thomas


Helge

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)





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