[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

[Jani Nikula]

On Tue, 11 May 2021, Kai-Heng Feng <kai.heng.feng at canonical.com> wrote:
> On Tue, May 11, 2021 at 2:06 AM Albert Astals Cid <aacid at kde.org> wrote:
>>
>> Yes, I also have the same.
>>
>> I git bisected that and found this to be the cause, i started a new email thread because i couldn't find this email ^_^
>
> Should be fixed by
> https://cgit.freedesktop.org/drm-tip/commit/?id=acca7762eb71bc05a8f28d29320d193150051f79

I've picked up acca7762eb71 ("drm/i915/dp: Use slow and wide link
training for everything") to drm-intel-fixes, and it should find itself
in v5.13-rc2 and subsequently v5.12 stable in the coming weeks.

BR,
Jani.


>
> Kai-Heng
>
>>
>> Cheers,
>>   Albert
>>
>> El dilluns, 10 de maig de 2021, a les 10:07:33 (CEST), Emanuele Panigati va escriure:
>> > 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
>> > >
>> >
>>
>>
>>
>>

-- 
Jani Nikula, Intel Open Source Graphics Center