[PATCH] drm/i915/vlv: Enable/disable VGA hotplugging properly

[Ville Syrjälä]

On Fri, Apr 15, 2016 at 09:47:51AM -0400, Lyude Paul wrote:
> Looks like we might not need to worry about this patch anymore actually, looks
> like this problem got fixed by accident by one of the other vlv fixes you
> pushed.

Not sure what exactly changed for you, but we definitely need to
reinitialize ADPA when re-enabling the power well.

> Now it's not always modesetting on hotplug when it was before though :(,
> so I'll get to work on bisecting that.
> 
> On Thu, 2016-04-14 at 20:59 +0300, Ville Syrjälä wrote:
> > On Tue, Mar 29, 2016 at 04:46:30PM -0400, Lyude wrote:
> > > 
> > > On Valleyview, VGA hotplugging is controlled through a seperate register
> > > than everything else, VLV_ADPA, which must be explicitly set.
> > > 
> > > While VGA hotplugging worked(ish) before, it looks like that was mainly
> > > because we'd unintentionally enable it in
> > > valleyview_crt_detect_hotplug() when we did a force trigger. This
> > > doesn't work reliably enough because whenever the display powerwell on
> > > vlv gets disabled, the values set in VLV_ADPA get cleared and
> > > consequently VGA hotplugging gets disabled. This causes bugs such as one
> > > we found on an Intel NUC, where doing the following sequence of
> > > hotplugs:
> > > 
> > > 	- Disconnect all monitors
> > > 	- Connect VGA
> > > 	- Disconnect VGA
> > > 	- Connect HDMI
> > > 
> > > Would result in hotplugging getting disabled, due to the display
> > > powerwells getting toggled in the process of connecting HDMI.
> > > 
> > > CC: stable at vger.kernel.org
> > > Signed-off-by: Lyude <cpaul at redhat.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_irq.c | 14 ++++++++++++++
> > >  1 file changed, 14 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_irq.c
> > > b/drivers/gpu/drm/i915/i915_irq.c
> > > index 5aa4239..60592a4 100644
> > > --- a/drivers/gpu/drm/i915/i915_irq.c
> > > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > > @@ -3611,6 +3611,7 @@ static void valleyview_display_irqs_install(struct
> > > drm_i915_private *dev_priv)
> > >  {
> > >  	u32 pipestat_mask;
> > >  	u32 iir_mask;
> > > +	u32 adpa_reg;
> > >  	enum pipe pipe;
> > >  
> > >  	pipestat_mask = PIPESTAT_INT_STATUS_MASK |
> > > @@ -3627,6 +3628,12 @@ static void valleyview_display_irqs_install(struct
> > > drm_i915_private *dev_priv)
> > >  	for_each_pipe(dev_priv, pipe)
> > >  		      i915_enable_pipestat(dev_priv, pipe, pipestat_mask);
> > >  
> > > +	if (IS_VALLEYVIEW(dev_priv)) {
> > > +		adpa_reg = I915_READ(VLV_ADPA);
> > > +		adpa_reg |= ADPA_CRT_HOTPLUG_ENABLE;
> > > +		I915_WRITE(VLV_ADPA, adpa_reg);
> > > +	}
> > We might not want to enable that when there's no VGA connector.
> > 
> > Seems like we should just be calling intel_crt_reset() here. We
> > definitely don't want to call the reset for hooks for all the other
> > connectors so drm_mode_config_reset() is out. Also the connector
> > locking might be problematic here, so I might suggest adjusting
> > intel_crt_reset() to take an encoder instead of connector, and then
> > we should be able to walk the encoder list without any troubles.
> > 
> > > 
> > > +
> > >  	iir_mask = I915_DISPLAY_PORT_INTERRUPT |
> > >  		   I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
> > >  		   I915_DISPLAY_PIPE_B_EVENT_INTERRUPT;
> > > @@ -3645,8 +3652,15 @@ static void valleyview_display_irqs_uninstall(struct
> > > drm_i915_private *dev_priv)
> > >  {
> > >  	u32 pipestat_mask;
> > >  	u32 iir_mask;
> > > +	u32 adpa_reg;
> > >  	enum pipe pipe;
> > >  
> > > +	if (IS_VALLEYVIEW(dev_priv)) {
> > > +		adpa_reg = I915_READ(VLV_ADPA);
> > > +		adpa_reg &= ~ADPA_CRT_HOTPLUG_ENABLE;
> > > +		I915_WRITE(VLV_ADPA, adpa_reg);
> > > +	}
> > > +
> > >  	iir_mask = I915_DISPLAY_PORT_INTERRUPT |
> > >  		   I915_DISPLAY_PIPE_A_EVENT_INTERRUPT |
> > >  		   I915_DISPLAY_PIPE_B_EVENT_INTERRUPT;
> > > -- 
> > > 2.5.5
> > > 
> > > _______________________________________________
> > > dri-devel mailing list
> > > dri-devel at lists.freedesktop.org
> > > https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Ville Syrjälä
Intel OTC