[Intel-gfx] [PATCH 2/5] drm/i915/dp: Restrict link retrain workaround to external monitors

[Pandiyan, Dhinakaran]

On Tue, 2018-09-18 at 08:50 -0700, Rodrigo Vivi wrote:
> On Tue, Sep 18, 2018 at 11:33:24AM -0400, Lyude Paul wrote:
> > Did the patch this references get pushed? I saw it fly by and I
> > thought we had
> > decided not to pull it in
> 
> ops, I created the confusion. Sorry.
> 
> What I decided that week was to not pull to drm-intel-fixes until
> Ville
> or Jani acking. But it was already part of dinq, so moving to drm-
> next
> and I didn't removed or reverted it.

I would have preferred to limit this work around to the specific
monitor it was needed for. The next best thing is to at least limit it
to external monitors? The code adds a bunch of extra dpcd reads to
check link status and acquires locks whenever user spaces wants a
->detect() and most sinks do not need this.

Let me know what your thoughts are.

-DK


> 
> So... But ville acked on irc and I pulled to -fixes on the following
> week
> as well.
> 
> So yes, patch is there ;)
> 
> > 
> > On Tue, 2018-09-18 at 00:20 -0700, Dhinakaran Pandiyan wrote:
> > > commit '3cf71bc9904d ("drm/i915: Re-apply "Perform link quality
> > > check,
> > > unconditionally during long pulse"")' applies a work around for
> > > monitors
> > > that don't signal link loss. Limit this only for external
> > > displays as
> > > eDP features like PSR when active will have the link turned off
> > > and the
> > > driver ends up retraining the link seeeing that link is not
> > > synchronized.
> > > 
> > > Cc: Lyude Paul <lyude at redhat.com>
> > > Cc: Jan-Marek Glogowski <glogow at fbihome.de>
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > > References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link
> > > quality check,
> > > unconditionally during long pulse"")
> > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com
> > > >
> > > ---
> > >  drivers/gpu/drm/i915/intel_dp.c | 4 +++-
> > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > > b/drivers/gpu/drm/i915/intel_dp.c
> > > index cac1c7c6cbfd..8bf9afa5683c 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -5072,7 +5072,9 @@ intel_dp_long_pulse(struct intel_connector
> > > *connector,
> > >  		 */
> > >  		status = connector_status_disconnected;
> > >  		goto out;
> > > -	} else {
> > > +	}
> > > +
> > > +	if (!intel_dp_is_edp(intel_dp)) {
> > >  		/*
> > >  		 * Some monitors do not signal loss of link
> > > synchronization
> > >  		 * with an IRQ_HPD, so force a link status
> > > check.
> > 
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