Re: [PATCH 2/2] drm/ofdrm: Update expected device name

[Helge Deller]

On 4/24/23 11:07, Thomas Zimmermann wrote:
> Hi
>
> Am 24.04.23 um 09:33 schrieb Geert Uytterhoeven:
> > Hi Cyril,
> >
> > CC DT
> >
> > On Wed, Apr 12, 2023 at 12:05 PM Cyril Brulebois <cyril@xxxxxxxxxxx> wrote:
> > > Since commit 241d2fb56a18 ("of: Make OF framebuffer device names unique"),
> > > as spotted by Frédéric Bonnard, the historical "of-display" device is
> > > gone: the updated logic creates "of-display.0" instead, then as many
> > > "of-display.N" as required.
> > >
> > > This means that offb no longer finds the expected device, which prevents
> > > the Debian Installer from setting up its interface, at least on ppc64el.
> > >
> > > Given the code similarity it is likely to affect ofdrm in the same way.
> > >
> > > It might be better to iterate on all possible nodes, but updating the
> > > hardcoded device from "of-display" to "of-display.0" is likely to help
> > > as a first step.
> > >
> > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=217328
> > > Link: https://bugs.debian.org/1033058
> > > Fixes: 241d2fb56a18 ("of: Make OF framebuffer device names unique")
> > > Cc: stable@xxxxxxxxxxxxxxx # v6.2+
> > > Signed-off-by: Cyril Brulebois <cyril@xxxxxxxxxxx>
> >
> > Thanks for your patch, which is now commit 3a9d8ea2539ebebd
> > ("drm/ofdrm: Update expected device name") in fbdev/for-next.
> >
> > > --- a/drivers/gpu/drm/tiny/ofdrm.c
> > > +++ b/drivers/gpu/drm/tiny/ofdrm.c
> > > @@ -1390,7 +1390,7 @@ MODULE_DEVICE_TABLE(of, ofdrm_of_match_display);
> > >
> > >   static struct platform_driver ofdrm_platform_driver = {
> > >          .driver = {
> > > -               .name = "of-display",
> > > +               .name = "of-display.0",
> > >                  .of_match_table = ofdrm_of_match_display,
> > >          },
> > >          .probe = ofdrm_probe,
> >
> > Same comment as for "[PATCH 1/2] fbdev/offb: Update expected device
> > name".
> >
> > https://lore.kernel.org/r/CAMuHMdVGEeAsmb4tAuuqqGJ-4+BBETwEwYJA+M9NyJv0BJ_hNg@xxxxxxxxxxxxxx
>
> Sorry that I missed this patch. I agree that it's probably not
> correct. At least in ofdrm, we want to be able to use multiple
> framebuffers at the same time; a feature that has been broken by this
> change.

Geert & Thomas, thanks for the review!

I've dropped both patches from fbdev tree for now.
Would be great to find another good solution though, as it breaks the debian
installer.

Helge