[Intel-gfx] [PATCH 1/5] drm/i915/dp: Fix link retraining comment in intel_dp_long_pulse()

[Pandiyan, Dhinakaran]

On Tue, 2018-09-18 at 08:51 -0700, Rodrigo Vivi wrote:
> On Tue, Sep 18, 2018 at 12:20:05AM -0700, Dhinakaran Pandiyan wrote:
> > Comment claims link needs to be retrained because the connected
> > sink raised
> > a long pulse to indicate link loss. If the sink did so,
> > intel_dp_hotplug() would have handled link retraining. Looking at
> > the
> > logs in Bugzilla referenced in commit '3cf71bc9904d ("drm/i915: Re-
> > apply
> > Perform link quality check, unconditionally during long pulse"")',
> > the
> > issue is that the sink does not trigger an interrupt. We want the
> > ->detect() from user space to check link status and retrain.
> > Ville's
> > review for the original patch also indicates the same root cause.
> > 
> > I have also renamed long_pulse() to full_detect().
> 
> have you?!
> I just see the comment change on this patch ;)
> 
> 
> > v2: Patch split and rewrote comment..
I split the renaming part. I'll rewrite the commit message if you want
me to.



> > 
> > Cc: Lyude Paul <lyude at redhat.com>
> > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > Cc: Jani Nikula <jani.nikula at linux.intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > Cc: Jan-Marek Glogowski <glogow at fbihome.de>
> > 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 | 12 ++----------
> >  1 file changed, 2 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > b/drivers/gpu/drm/i915/intel_dp.c
> > index 436c22de33b6..cac1c7c6cbfd 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -5074,16 +5074,8 @@ intel_dp_long_pulse(struct intel_connector
> > *connector,
> >  		goto out;
> >  	} else {
> >  		/*
> > -		 * If display is now connected check links status,
> > -		 * there has been known issues of link loss
> > triggering
> > -		 * long pulse.
> > -		 *
> > -		 * Some sinks (eg. ASUS PB287Q) seem to perform
> > some
> > -		 * weird HPD ping pong during modesets. So we can
> > apparently
> > -		 * end up with HPD going low during a modeset, and
> > then
> > -		 * going back up soon after. And once that happens
> > we must
> > -		 * retrain the link to get a picture. That's in
> > case no
> > -		 * userspace component reacted to intermittent HPD
> > dip.
> > +		 * Some monitors do not signal loss of link
> > synchronization
> > +		 * with an IRQ_HPD, so force a link status check.
> >  		 */
> >  		struct intel_encoder *encoder =
> > &dp_to_dig_port(intel_dp)->base;
> >  
> > -- 
> > 2.14.1
> > 
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> > Intel-gfx at lists.freedesktop.org
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