[PATCH/RFC 0/3] Atari DRM driver

[Geert Uytterhoeven]

Hi Eero,

On Wed, 21 May 2025 at 01:59, Eero Tamminen <oak at helsinkinet.fi> wrote:
> On 23.1.2023 17.10, Geert Uytterhoeven wrote:
> > On Mon, Jan 23, 2023 at 4:09 PM John Paul Adrian Glaubitz
> > <glaubitz at physik.fu-berlin.de> wrote:
> >> On 11/25/22 21:31, Geert Uytterhoeven wrote:
> >>> This RFC patch series adds a DRM driver for the good old Atari
> >>> ST/TT/Falcon hardware.  It was developed and tested (only) on the ARAnyM
> >>> emulator.
> >>
> >> I just remembered this WIP driver. Has there been any progress?
> >
> > So far no further progress.
>
> I tried your "atari-drm-wip-v1" branch commits on top of 6.14.

Thanks for testing!

> After some minor changes those applied. Getting it to build required
> adding "&shadow_plane_state->fmtcnv_state" (struct drm_format_conv_state
> *) argument to *_blit() functions in atari_drm.c, and changing:
>         drm_fbdev_generic_setup(dev, dev->mode_config.preferred_depth);
> in its probe function to:
>         struct drm_format_info *format = NULL;
>          drm_client_setup(dev, format);

I do keep it up-to-date locally, so I could provide these changes,
if you are interested.

> However, the result is not working very well yet.
>
> Driver gets initialized fine under Hatari TT emulation:
> -------------------------
> atafb atafb: phys_screen_base 511000 screen_len 311296
> atafb atafb: Determined 1280x960, depth 1
> atafb atafb:    virtual 1280x1945
> Console: switching to mono frame buffer device 160x60
> fb0: frame buffer device, using 304K of video memory
> ...
> atari_drm atari_drm: phys_screen_base 55d000 screen_len 311296
> atari_drm atari_drm: Determined 1280x960, depth 1
> atari_drm atari_drm:    virtual 1280x1945
> [drm] Initialized atari_drm 1.0.0 for atari_drm on minor 0
> atari_drm atari_drm: Atari DRM, using 304K of video memory
> -------------------------
>
> However, once screen switches from "atafb" to "atari_drm" driver, Linux
> boot logo & texts disappear, and (emulated) screen is either all white
> (on mono monitor) or all black (on VGA & RGGB monitors).

So you have both atafb and atari_drm enabled? Please don't do that.

> And while "atafb" works fine also under Falcon emulation with RGB (50Hz)
> or VGA (60Hz) monitor, "atari_drm" probing fails:
> -------------------------
> genirq: Flags mismatch irq 4. 00200000 (framebuffer:modeswitch) vs.
> 00200000 (framebuffer:modeswitch)

That's also a sign of two drivers requesting the same IRQ unexpectedly.

> atari_drm atari_drm: probe with driver atari_drm failed with error -16

i.e. -EBUSY.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at 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