Re: [PATCH 2/2] drm/i915/display: allow eDP VRR when EDID has adaptive sync range

[Jake S <j@metarealtyinc.ca>]

Hi Ville,

> AFAICS the Windows driver does respect that VBT bit. So we should too.

That's fair -- I don't have visibility into the Windows driver
internals so I can't say definitively whether it checks VBT or not.

What I can confirm is the end-user result: on this Dell XPS 2026
(Panther Lake), VRR 20-120Hz works on Windows but not on Linux with
the same firmware. The VBT does not contain a VRR flag for this panel
at all -- intel_vbt_decode shows no VRR-related fields in the child
device block.

So either Windows has a fallback path when VBT doesn't declare VRR,
or Dell's Intel DCH driver ships with a driver-side override. Either
way, the panel clearly supports VRR (the EDID's DisplayID extension
explicitly declares Adaptive Sync 20-120Hz), and it works in practice
on this hardware.

Framework laptop users have reported the same class of issue with
their BOE panels.

If respecting VBT is important (and I understand the reasoning --
OEM validation), would something like a quirk table or a module
parameter be an acceptable alternative? I'd rather have any path to
making this work than no path.

Thanks for the review.

Jake