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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Apr 15, 2026 at 07:08:30PM +0000, Jake S wrote:
> 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.

It's in the LFP power block (44).

> 
> 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.

My cursory glance didn't spot any registry key stuff in there
either. That I think is the usual "screw proper design and just
hack it" approach for the Windows driver.

> 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.

One can always hack up the VBT and use the firmware loader
to override it.

-- 
Ville Syrjälä
Intel