Re: [REGRESSION] 7.1: apple-gmux backlight dead on MacBookPro13,3 - PCI bridge left with VGA enable set and VGA 16-bit decode cleared, aliasing legacy VGA I/O over the gmux ports

Jani Nikula <[email protected]> Tue, 04 Aug 2026 16:12:58 +0300

Newsgroups	gmane.comp.freedesktop.xorg.drivers.intel,gmane.comp.video.dri.devel
Organization	Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland
Message-ID	<[email protected]>

On Tue, 04 Aug 2026, Haram Choi <[email protected]> wrote:
> I think I have found the commit. It is not in drivers/pci at all, and
> my previous suspicion of 94555ea9a048 was wrong. Apologies to Simon
> for the noise.
>
> The regression is:
>
>   cc6ed470caa2 ("drm/i915/vga: Avoid VGA arbiter during
>                  intel_vga_disable() for iGPUs")
>   Ville Syrjala <[email protected]>, 2025-12-08

Uh, that's a bit of a bummer. As you can see, I've only acked it,
because quite honestly, I don't fully understand what's going on, but I
fully trust Ville to follow through with any issues it might cause. Like
this one. However, Ville's not available for a few weeks now, and the
commit also does not revert cleanly anymore.

We can either try to hack together some sort of fix/revert, or wait for
Ville's input.

BR,
Jani.

-- 
Jani Nikula, Intel