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

[Lyude Paul]

SGTM

On Wed, 2018-09-19 at 17:58 +0000, Pandiyan, Dhinakaran wrote:
> 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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> > > Intel-gfx at lists.freedesktop.org
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