On Thu, Jun 04, 2020 at 05:55:30PM +0300, Ville Syrjälä wrote:
> On Thu, Jun 04, 2020 at 12:10:38AM +0300, Imre Deak wrote:
> > Currently MST on a port can get enabled/disabled from the hotplug work
> > and get disabled from the short pulse work in a racy way. Fix this by
> > relying on the MST state checking in the hotplug work and just schedule
> > a hotplug work from the short pulse handler if some problem happened
> > during the MST interrupt handling.
> > 
> > This removes the explicit MST disabling in case of an AUX failure, but
> > if AUX fails, then probably the detection will also fail during the
> > scheduled hotplug work and it's not guaranteed that we'll see
> > intermittent errors anyway.
> > 
> > While at it also simplify the error checking of the MST interrupt
> > handler.
> > 
> > Signed-off-by: Imre Deak <imre.d...@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp.c | 33 +++----------------------
> >  1 file changed, 4 insertions(+), 29 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c 
> > b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 55fda074c0ad..befbcacddaa1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -5604,7 +5604,7 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
> >             }
> >     }
> >  
> > -   return need_retrain;
> > +   return need_retrain ? -EINVAL : 0;
> >  }
> >  
> >  static bool
> > @@ -7255,35 +7255,10 @@ intel_dp_hpd_pulse(struct intel_digital_port 
> > *intel_dig_port, bool long_hpd)
> >     }
> >  
> >     if (intel_dp->is_mst) {
> > -           switch (intel_dp_check_mst_status(intel_dp)) {
> > -           case -EINVAL:
> > -                   /*
> > -                    * If we were in MST mode, and device is not
> > -                    * there, get out of MST mode
> > -                    */
> > -                   drm_dbg_kms(&i915->drm,
> > -                               "MST device may have disappeared %d vs 
> > %d\n",
> > -                               intel_dp->is_mst,
> > -                               intel_dp->mst_mgr.mst_state);
> > -                   intel_dp->is_mst = false;
> > -                   drm_dp_mst_topology_mgr_set_mst(&intel_dp->mst_mgr,
> > -                                                   intel_dp->is_mst);
> > -
> > -                   return IRQ_NONE;
> > -           case 1:
> > -                   return IRQ_NONE;
> > -           default:
> > -                   break;
> > -           }
> > -   }
> > -
> > -   if (!intel_dp->is_mst) {
> > -           bool handled;
> > -
> > -           handled = intel_dp_short_pulse(intel_dp);
> > -
> > -           if (!handled)
> > +           if (intel_dp_check_mst_status(intel_dp) < 0)
> >                     return IRQ_NONE;
> 
> Since we no longer need the tristate return, can you follow up
> with a conversion to bool return? I'd vote to make it match the
> semantics of intel_dp_short_pulse() so we get one step
> closer to unifying the hpd_irq handling across the board.

Ok, makes sense.

> 
> > +   } else if (!intel_dp_short_pulse(intel_dp)) {
> > +           return IRQ_NONE;
> >     }
> >  
> >     return IRQ_HANDLED;
> > -- 
> > 2.23.1
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > intel-...@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel
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