[Intel-gfx] [PATCH 1/2] drm/i915: Try to use fast+narrow link on eDP again and fall back to the old max strategy on failure

[Emanuele Panigati]

Hi,
  on my Dell XPS 15 9570 laptop I might have a regression with Arch Linux
(kernel 5.12.2-arch1-1: during boot the laptop monitor goes black while
external monitors still works...


Panich


Il giorno lun 11 gen 2021 alle ore 19:28 Ville Syrjälä <
ville.syrjala at linux.intel.com> ha scritto:

> On Thu, Jan 07, 2021 at 08:20:25PM +0200, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >
> > Some new eDP panels don't like to operate at the max parameters, and
> > instead we need to go for an optimal confiugration. That unfortunately
> > doesn't work with older eDP panels which are generally only guaranteed
> > to work at the max parameters.
> >
> > To solve these two conflicting requirements let's start with the optimal
> > setup, and if that fails we start again with the max parameters. The
> > downside is probably an extra modeset when we switch strategies but
> > I don't see a good way to avoid that.
> >
> > For a bit of history we first tried to go for the fast+narrow in
> > commit 7769db588384 ("drm/i915/dp: optimize eDP 1.4+ link config
> > fast and narrow"). but that had to be reverted due to regression
> > on older panels in commit f11cb1c19ad0 ("drm/i915/dp: revert back
> > to max link rate and lane count on eDP"). So now we try to get
> > the best of both worlds by using both strategies.
>
> Pushed. Fingers crossed for no regressions...
>
> --
> Ville Syrjälä
> Intel
>
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