# Re: \[PATCH\] fbdev: udl: Make CONFIG\_FB\_DEVICE optional

- From: Thomas Zimmermann \<tzimmermann@suse.de\>
- Date: 2024-11-01 08:19:26 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2024/11/9254624
- Thread: https://ratatoskr.run/linux-fbdev/2024/10/9254479/t.md

```text
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)

```