On Fri, 2018-09-07 at 17:32 +0300, Ville Syrjälä wrote: > On Fri, Sep 07, 2018 at 03:39:24PM +0300, Jani Nikula wrote: > > On Thu, 06 Sep 2018, Dhinakaran Pandiyan <dhinakaran.pandiyan@intel > > .com> 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(). > > > > Since intel_dp_detect() doesn't actually do *anything* except skip > > detect sometimes, I think "full detect" is a misnomer. > > > > Arguably you could merge intel_dp_long_pulse() into its only > > caller, > > intel_dp_detect(), and do an early return on skipping detect. You > > have > > to look at the functions, and wonder if the current split is the > > right > > one. > > That's pretty much what I suggested earlier. I had mixed feelings when I wrote it, but merging the functions does sound like a better idea now. > Although someone should > double check to make sure the detect_done flag even makes sense these > days. Maybe it does, maybe it doesn't, I don't recall. It doesn't afaict. The only place where detect_done gets set to true is followed by resetting of the flag to false. -DK > > > > > Please let others chime in too before making changes. > > > > BR, > > Jani. > > > > > > > > > > Cc: Lyude Paul <lyude@xxxxxxxxxx> > > > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> > > > Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> > > > Cc: Jan-Marek Glogowski <glogow@xxxxxxxxxx> > > > References: 3cf71bc9904d ("drm/i915: Re-apply "Perform link > > > quality check, unconditionally during long pulse"") > > > Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx > > > > > > > --- > > > drivers/gpu/drm/i915/intel_dp.c | 17 +++++------------ > > > 1 file changed, 5 insertions(+), 12 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/i915/intel_dp.c > > > b/drivers/gpu/drm/i915/intel_dp.c > > > index 436c22de33b6..befdaa076d8c 100644 > > > --- a/drivers/gpu/drm/i915/intel_dp.c > > > +++ b/drivers/gpu/drm/i915/intel_dp.c > > > @@ -5012,7 +5012,7 @@ intel_dp_unset_edid(struct intel_dp > > > *intel_dp) > > > } > > > > > > static int > > > -intel_dp_long_pulse(struct intel_connector *connector, > > > +intel_dp_full_detect(struct intel_connector *connector, > > > struct drm_modeset_acquire_ctx *ctx) > > > { > > > struct drm_i915_private *dev_priv = to_i915(connector- > > > >base.dev); > > > @@ -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. > > > + * Check link status in case the link went out > > > of > > > + * synchronization and the sink did not tell us. > > > */ > > > struct intel_encoder *encoder = > > > &dp_to_dig_port(intel_dp)->base; > > > > > > @@ -5149,7 +5141,8 @@ intel_dp_detect(struct drm_connector > > > *connector, > > > return ret; > > > } > > > > > > - status = intel_dp_long_pulse(intel_dp- > > > >attached_connector, ctx); > > > + status = intel_dp_full_detect(intel_dp- > > > >attached_connector, > > > + ctx); > > > } > > > > > > intel_dp->detect_done = false; > > > > -- > > Jani Nikula, Intel Open Source Graphics Center > > _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx