Re: [PATCH] drm/i915: Calculate CDCLK on modeset after sanitizing pre-os programming

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

On Wed, Jun 24, 2026 at 09:47:39AM +0300, Joonas Lahtinen wrote:
> Quoting Ville Syrjälä (2026-06-23 17:24:43)
> > This smells like the same thing I already fixed with
> > commit 3f9de66f8acb ("drm/i915/cdclk: Fix up CDCLK_FREQ_DECIMAL
> > without a full PLL re-enable")
> > 
> > Sadly it looks like I forgot to cc:stable it :/
> > 
> > Jani, can you pick that up for -fixes and slap a cc:stable on it?
> 
> I'll include it in drm-intel-next-fixes, do we have a
> Fixes: tag to add?

It's been basically broken forever so the correct fixes
tags probably aren't super useful.

However the nastier user visible regression happened in 
commit ba91b9eecb47 ("drm/i915/cdclk: Decouple cdclk from
state->modeset") which therefore might make sense as a
fixes tag. But if we put that in then I'm worried that it
won't get backported to older kernels. I guess we could throw
that in there along with the ancient commits that actually
introduced the problem.

So something along the lines of:
Fixes: ba91b9eecb47 ("drm/i915/cdclk: Decouple cdclk from state->modeset")
Fixes: d66a21947e21 ("drm/i915/bxt: Sanitize CDCLK to fix breakage during S4 resume")
Fixes: c73666f394fc ("drm/i915/skl: If needed sanitize bios programmed cdclk")

-- 
Ville Syrjälä
Intel