[Intel-gfx] [PATCH] drm/i915/dp: Reset link params on connector disconnect

[Imre Deak]

On Thu, Jun 04, 2020 at 10:08:58PM +0300, Imre Deak wrote:
> On Thu, Jun 04, 2020 at 10:01:40PM +0300, Ville Syrjälä wrote:
> > [...]
> > > > Then we get this hpd, in this case if we dont reset the param to max values, prev triggered modeset continues
> > > > with fallback values but since connector probe doesnt happen again through IGT, it tries the same mode
> > > > with fallback values and return encoder config failure.
> > > 
> > > If the link training failed then clearly the sink didn't like us anymore
> > > anyway. So feels like resetting these here is just shifting some race
> > > window around a bit, but it could still fail if the sink still doesn't
> > > like us.
> > > 
> > > Would be good if someone was able to figure out why the sink goes bad in
> > > the first place.
> > 
> > Oh, and don't we now have Imre's "weird hpd happened in the middle of
> > the test, don't trust the results" thing in igt?
> 
> An LG and IIyama monitor this happens on disconnect and reconnect after
> waking from an idle state when modesetting them, not sure if it's the
> same case.

Manasi, could you try if a modeset on the monitor after it has been
disabled for a while always results in a long HPD pulse a few seconds
after the modeset? If so does this also happen when you just modeset in
a sequence from one mode to the other not letting the monitor idle? The
same monitor should be also tested then with the above sequences on
older platforms if it behaves the same on those too.

> 
> --Imre
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