Hi Eero,
On Thu, 29 May 2025 at 02:06, Eero Tamminen <o...@helsinkinet.fi> wrote:
> On 28.5.2025 11.57, Geert Uytterhoeven wrote:
> > On Wed, 28 May 2025 at 00:47, Eero Tamminen <o...@helsinkinet.fi> wrote:
> >> I did boot testing on Hatari emulator with a minimal kernel config
> >> having atari_drm enabled, atafb disabled, FB & boot logo enabled.
> >>
> >> Under Falcon emulation:
> >> - RGB/VGA => works fine
> >> - Mono monitor => panic
> >> "Kernel panic - not syncing: can't set default video mode"
> >>
> >> Under TT emulation:
> >> - RGB/VGA => boots, but console is black[1] (palette issue?)
> >> - Mono monitor => looks OKish[2], but has constant warnings:
> >> -----------------------------------
> >> WARNING: CPU: 0 PID: 1 at drivers/gpu/drm/drm_atomic_helper.c:1720
> >> drm_atomic_helper_wait_for_vblanks+0x1a0/0x1ee
> >> [CRTC:35:crtc-0] vblank wait timed out
> >
> > I am not sure this is a bug in atari-drm, or just an issue when using
> > DRM on slow machines.
>
> This does not trigger with -Os built "atafb" kernel, but happens even
> with -O2 built "atari-drm" kernel. Something related to the higher (71)
> HZ of the mono monitors?
>
> (I don't think it relates to TT mono monitor's larger 1280x960
> resolution, because it happens also with ST mono monitor 640x400 one.)
DRM vblank handling is part of DRM, so it is not applicable to atafb.
> > Are these regression in atari-drm, or do they happen with atafb, too?
>
> Only the "can't set default video" issue in Falcon mono mode happens
> also with "atafb".
>
> It has neither the above vblank timeout issue in mono mode, nor
> black-on-black color issue in color mode (on TT and 030 ST).
Unless I made a mistake, color handling should be the same for
atari-drm and atafb. Unfortunately I am no Atari hardware expert.
> >> However, -O2 build has the downside that the resulting kernel Oopses
> >> once it reaches user-space, if 030 data cache emulation is enabled:
> >> ----------------------------------------------------------------
> >> Run /init as init process
> >> ...
> >> Instruction fault at 0x0041a256
> >> BAD KERNEL BUSERR
> >
> > Interesting...
>
> 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.
Logo shouldn't matter.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@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
