Re: [PATCH 1/3] drm/i915/icl: Release TC ports when unloading or suspending driver

[Imre Deak <imre.deak@intel.com>]

On Wed, Nov 28, 2018 at 11:54:21PM +0200, Souza, Jose wrote:
> On Wed, 2018-11-28 at 13:34 +0200, Imre Deak wrote:
> > On Wed, Nov 07, 2018 at 04:05:52PM -0800, José Roberto de Souza
> > wrote:
> > > When suspending or unloading the driver, it needs to release the
> > > TC ports so HW can change it state without wait for driver
> > > handshake.
> > 
> > According to 
> > https://bugs.freedesktop.org/show_bug.cgi?id=108070#c26
> > 
> > this patch should fix the bug reported at
> > https://bugs.freedesktop.org/show_bug.cgi?id=108070#c17
> > 
> > but, I can't see how the change here would fix the corresponding
> > problem
> > described in
> > https://bugs.freedesktop.org/show_bug.cgi?id=108070#c18
> > 
> > Would you explain?
> > 
> > I think there are more fundamental problems in TypeC HPD handling as
> > we
> > discussed earlier here on the list, which should be fixed first:
> > 
> > - Switching to/from type C mode from the interrupt handler without
> >   considering if we have an active mode or an ongoing AUX transfer.
> 
> Yes that is still missing, I plan to work on that after I deliver a few
> tasks. Also I read the emails in discussion that you started about
> that.

The point is that imo those fundamental problems should be fixed first.

> 
> > 
> > - Not having any way for handling the case where we'd do a modeset
> > after
> >   an HPD disconnect interrupt, like in the case of
> >   common-hpd-after-suspend in the bug report.
> 
> For what I understood about this test it will suspend, disconnect
> chamelium board from source, wakeup and check if connector state match,
> as we did not marked port as safe before suspending we are left in a
> invalid state where PD firmware do not trigger a interruption after
> wakeup.

No, it's not about the lack of HPD interrupts. What happens is that the
sink disappears during system suspend/resume, but we still have an
active mode enabled on the corresponding port. We try to restore this
mode during resume but that modeset will fail.

> 
> > 
> > More comments below:
> > 
> > > Cc: Imre Deak <imre.deak@intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/i915_drv.c      |  1 +
> > >  drivers/gpu/drm/i915/i915_drv.h      |  1 +
> > >  drivers/gpu/drm/i915/i915_irq.c      |  1 +
> > >  drivers/gpu/drm/i915/intel_dp.c      | 19 +++++++++++++++++++
> > >  drivers/gpu/drm/i915/intel_drv.h     |  1 +
> > >  drivers/gpu/drm/i915/intel_hotplug.c |  9 +++++++++
> > >  6 files changed, 32 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.c
> > > b/drivers/gpu/drm/i915/i915_drv.c
> > > index acb516308262..14331c396278 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.c
> > > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > > @@ -1911,6 +1911,7 @@ static int i915_drm_suspend(struct drm_device
> > > *dev)
> > >  
> > >  	intel_runtime_pm_disable_interrupts(dev_priv);
> > >  	intel_hpd_cancel_work(dev_priv);
> > > +	intel_hpd_suspend(dev_priv);
> > 
> > What about runtime suspend? We won't receive HPD interrupts after
> > that
> > either, so we'd need to disconnect in that case too according to the
> > spec.
> 
> Oh my bad I was thinking that the regular suspend would handle this too
> but I was wrong.
> 
> So I will add a intel_hpd_suspend() call to intel_runtime_suspend()
> leaving the i915_drv.c changes as this.
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c
> b/drivers/gpu/drm/i915/i915_drv.c
> index b1d23c73c147..948914a79c67 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1905,6 +1905,7 @@ static int i915_drm_suspend(struct drm_device
> *dev)
> 
>         intel_runtime_pm_disable_interrupts(dev_priv);
>         intel_hpd_cancel_work(dev_priv);
> +       intel_hpd_suspend(dev_priv);
> 
>         intel_suspend_encoders(dev_priv);
> 
> @@ -2909,6 +2910,7 @@ static int intel_runtime_suspend(struct device
> *kdev)
>         intel_uc_suspend(dev_priv);
> 
>         intel_runtime_pm_disable_interrupts(dev_priv);
> +       intel_hpd_suspend(dev_priv);
> 
>         intel_uncore_suspend(dev_priv);
> 
> Also I will drop the next patch as we don't call
> intel_hpd_cancel_work() in intel_runtime_suspend() path.
> 
> 
> > 
> > And how are we handling resume then where we'll be in a disconnected
> > state due to the change in this patch and would continue to do a
> > modeset (to restore the mode we had before suspend).
> 
> The drm_kms_helper_poll_enable() calls will trigger the call to the
> detection function of the connectors that will call
> intel_digital_port_connected() thal will call ICL TC functions that
> will take care of update everything.

No detection will be triggered, since we're not polling this port (and
polling can be disabled as a whole). In any case that would be too late,
since we're trying to restore the mode before we call
drm_kms_helper_poll_enable().  Also doing a detection is not enough
here, since if detection fails (as it would in our case) we still have a
mode that we need to restore. The corresponding modeset would fail, but
we don't have a way to fail it gracefully as I wrote above.

> 
> > 
> > >  
> > >  	intel_suspend_encoders(dev_priv);
> > >  
> > > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > > b/drivers/gpu/drm/i915/i915_drv.h
> > > index 0c8438de3c1b..96d5ddc36f4e 100644
> > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > @@ -2792,6 +2792,7 @@ enum hpd_pin intel_hpd_pin_default(struct
> > > drm_i915_private *dev_priv,
> > >  				   enum port port);
> > >  bool intel_hpd_disable(struct drm_i915_private *dev_priv, enum
> > > hpd_pin pin);
> > >  void intel_hpd_enable(struct drm_i915_private *dev_priv, enum
> > > hpd_pin pin);
> > > +void intel_hpd_suspend(struct drm_i915_private *dev_priv);
> > >  
> > >  /* i915_irq.c */
> > >  static inline void i915_queue_hangcheck(struct drm_i915_private
> > > *dev_priv)
> > > diff --git a/drivers/gpu/drm/i915/i915_irq.c
> > > b/drivers/gpu/drm/i915/i915_irq.c
> > > index d7e47d6082de..23084d227e2a 100644
> > > --- a/drivers/gpu/drm/i915/i915_irq.c
> > > +++ b/drivers/gpu/drm/i915/i915_irq.c
> > > @@ -4996,6 +4996,7 @@ void intel_irq_uninstall(struct
> > > drm_i915_private *dev_priv)
> > >  {
> > >  	drm_irq_uninstall(&dev_priv->drm);
> > >  	intel_hpd_cancel_work(dev_priv);
> > > +	intel_hpd_suspend(dev_priv);
> > >  	dev_priv->runtime_pm.irqs_enabled = false;
> > >  }
> > >  
> > > diff --git a/drivers/gpu/drm/i915/intel_dp.c
> > > b/drivers/gpu/drm/i915/intel_dp.c
> > > index 5258c9d654f4..27c6163426d6 100644
> > > --- a/drivers/gpu/drm/i915/intel_dp.c
> > > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > > @@ -5043,6 +5043,25 @@ bool intel_digital_port_connected(struct
> > > intel_encoder *encoder)
> > >  	return false;
> > >  }
> > >  
> > > +/*
> > > + * intel_digital_port_force_disconnection - Used to force port
> > > disconnection or
> > > + * release any control from display driver before going to a state
> > > that driver
> > > + * will not handle interruptions.
> > > + */
> > > +void intel_digital_port_force_disconnection(struct intel_encoder
> > > *encoder)
> > > +{
> > > +	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> > > +	struct intel_digital_port *dig_port;
> > > +
> > > +	dig_port = enc_to_dig_port(&encoder->base);
> > > +	/* Skip fake MST ports */
> > > +	if (!dig_port)
> > > +		return;
> > > +
> > > +	if (INTEL_GEN(dev_priv) >= 11)
> > > +		icl_tc_phy_disconnect(dev_priv, dig_port);
> > > +}
> > > +
> > >  static struct edid *
> > >  intel_dp_get_edid(struct intel_dp *intel_dp)
> > >  {
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h
> > > b/drivers/gpu/drm/i915/intel_drv.h
> > > index 6772e9974751..bc30f107b430 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -1851,6 +1851,7 @@ bool intel_dp_read_dpcd(struct intel_dp
> > > *intel_dp);
> > >  int intel_dp_link_required(int pixel_clock, int bpp);
> > >  int intel_dp_max_data_rate(int max_link_clock, int max_lanes);
> > >  bool intel_digital_port_connected(struct intel_encoder *encoder);
> > > +void intel_digital_port_force_disconnection(struct intel_encoder
> > > *encoder);
> > >  
> > >  /* intel_dp_aux_backlight.c */
> > >  int intel_dp_aux_init_backlight_funcs(struct intel_connector
> > > *intel_connector);
> > > diff --git a/drivers/gpu/drm/i915/intel_hotplug.c
> > > b/drivers/gpu/drm/i915/intel_hotplug.c
> > > index 42e61e10f517..d6745b7b79d5 100644
> > > --- a/drivers/gpu/drm/i915/intel_hotplug.c
> > > +++ b/drivers/gpu/drm/i915/intel_hotplug.c
> > > @@ -655,3 +655,12 @@ void intel_hpd_enable(struct drm_i915_private
> > > *dev_priv, enum hpd_pin pin)
> > >  	dev_priv->hotplug.stats[pin].state = HPD_ENABLED;
> > >  	spin_unlock_irq(&dev_priv->irq_lock);
> > >  }
> > > +
> > > +void intel_hpd_suspend(struct drm_i915_private *dev_priv)
> > > +{
> > > +	struct drm_device *dev = &dev_priv->drm;
> > > +	struct intel_encoder *encoder;
> > > +
> > > +	for_each_intel_encoder(dev, encoder)
> > > +		intel_digital_port_force_disconnection(encoder);
> > > +}
> > > -- 
> > > 2.19.1
> > > 


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