[PATCH/RFC 0/3] Atari DRM driver

[Eero Tamminen]

Hi,

On 29.5.2025 3.06, Eero Tamminen wrote:
> On 28.5.2025 11.57, Geert Uytterhoeven wrote:
> There were some extra config differences between my builds for 6.15 
> "atafb" and your "atari-drm-wip-rebasing" branch.
> 
> After removing the ones I could:
> --------------------------------
> $ diff -ub .config.old .config | grep '^[-+]C'
> -CONFIG_I2C_HELPER_AUTO=y
> -CONFIG_LOGO=y
> -CONFIG_LOGO_LINUX_MONO=y
> -CONFIG_LOGO_LINUX_VGA16=y
> -------------------------------
> 
> Bus error issue went away.
> 
> => Could there be some issue with how logo and "atari-drm" code 
> interact, which could manifest when reaching user-space?
> 
> Note: I haven't tried enabling logo with "atafb" + -O2 build. I could 
> try that later on.

Tried that now.  Enabling logo config options for "atafb" kernel did not 
cause bus error with -O2.  It did not show logo though, the area where 
the logo was shown with "atari-drm", was just black.

=> No conclusive result on whether logo triggers the bus error.


As to boot time with minimal kernel booting on (emulated) 32Mhz Falcon, 
according to /proc/uptime...

"-Os" kernel build:
- atafb:     11.87s
- atari-drm: 21.04s

=> Nearly 80% slower.

"-O2" kernel build:
- atafb:     10.35s
- atari-drm: 11.42s

=> Only 10% slower.

I.e. difference in -Os / -O2 boot time is clearly due to "atari-drm" driver.


	- Eero