Re: [Intel-gfx] [PATCH v4 13/14] drm/i915/tc: Call TypeC port flush_work/cleanup without modeset locks held

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

On Thu, May 11, 2023 at 08:40:58PM +0300, Ville Syrjälä wrote:
> On Wed, May 10, 2023 at 05:10:22PM +0300, Imre Deak wrote:
> > On Wed, May 10, 2023 at 05:03:17PM +0300, Ville Syrjälä wrote:
> > > On Wed, May 10, 2023 at 01:31:30PM +0300, Imre Deak wrote:
> > > > Call the TypeC port flush_work and cleanup handlers without the modeset
> > > > locks held. These don't require the locks, as the work takes - as it
> > > > should be able to at any point in time - any locks it needs and by the
> > > > time cleanup is called and after cleanup returns the encoder is not in
> > > > use.
> > > > 
> > > > This is required by the next patch canceling a TypeC port work
> > > > synchronously during encoder suspend and shutdown, where the work can
> > > > take modeset locks as well, hence the canceling must be done without
> > > > holding the locks.
> > > > 
> > > > I also considered moving the modeset locking down to each encoder
> > > > suspend()/shutdown() hook instead, however locking the full modeset
> > > > state for each encoder separately would be odd, and the bigger change -
> > > > affecting all encoders - is beyond the scope of this patchset.
> > > 
> > > Hmm. What is it in the encoder shutdown/suspend hooks that
> > > actually needs the modeset locks?
> > 
> > In the case of intel_dp_encoder_suspend() for instance, I assume
> > nothing, since the VDD work and intel_pps_vdd_off_sync() should take
> > whatever locks they require.
> > 
> > So presumably most (all) of those could be made lockless. However, I
> > would like to leave that kind of change for a follow-up if possible, not
> > to affect in this patchset any other encoder types (again because of
> > possible need for CC stable).
> 
> Yeah sure.

Ok, will add a TODO comment about this.

> A bit irksome to have to add vfuncs and whatnot for
> it though, but it's not the end of the world.

Direct intel_tc calls from intel_suspend/shutdown_encoders didn't seem
ideal either, but can do that if you think that's better.

> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> > 
> > > 
> > > > 
> > > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/display/intel_ddi.c      | 27 +++++++++----------
> > > >  .../drm/i915/display/intel_display_types.h    | 12 +++++++++
> > > >  drivers/gpu/drm/i915/i915_driver.c            |  8 ++++++
> > > >  3 files changed, 33 insertions(+), 14 deletions(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> > > > index 813be957ed11b..7d09bd2412352 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> > > > @@ -4617,31 +4617,27 @@ static bool intel_ddi_is_tc(struct drm_i915_private *i915, enum port port)
> > > >  
> > > >  static void intel_ddi_encoder_suspend(struct intel_encoder *encoder)
> > > >  {
> > > > -	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > > -	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > > > -	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > > > -	enum phy phy = intel_port_to_phy(i915, encoder->port);
> > > > -
> > > >  	intel_dp_encoder_suspend(encoder);
> > > > +}
> > > >  
> > > > -	if (!intel_phy_is_tc(i915, phy))
> > > > -		return;
> > > > +static void intel_ddi_tc_encoder_suspend_complete(struct intel_encoder *encoder)
> > > > +{
> > > > +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > > +	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > > >  
> > > >  	intel_tc_port_flush_work(dig_port);
> > > >  }
> > > >  
> > > >  static void intel_ddi_encoder_shutdown(struct intel_encoder *encoder)
> > > >  {
> > > > -	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > > -	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> > > > -	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > > > -	enum phy phy = intel_port_to_phy(i915, encoder->port);
> > > > -
> > > >  	intel_dp_encoder_shutdown(encoder);
> > > >  	intel_hdmi_encoder_shutdown(encoder);
> > > > +}
> > > >  
> > > > -	if (!intel_phy_is_tc(i915, phy))
> > > > -		return;
> > > > +static void intel_ddi_tc_encoder_shutdown_complete(struct intel_encoder *encoder)
> > > > +{
> > > > +	struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
> > > > +	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > > >  
> > > >  	intel_tc_port_cleanup(dig_port);
> > > >  }
> > > > @@ -4908,6 +4904,9 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
> > > >  				    is_legacy ? "legacy" : "non-legacy");
> > > >  		}
> > > >  
> > > > +		encoder->suspend_complete = intel_ddi_tc_encoder_suspend_complete;
> > > > +		encoder->shutdown_complete = intel_ddi_tc_encoder_shutdown_complete;
> > > > +
> > > >  		if (intel_tc_port_init(dig_port, is_legacy) < 0)
> > > >  			goto err;
> > > >  	}
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > index 270c4c84a2920..88b2a55d19f21 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> > > > @@ -233,13 +233,25 @@ struct intel_encoder {
> > > >  	 * Called during system suspend after all pending requests for the
> > > >  	 * encoder are flushed (for example for DP AUX transactions) and
> > > >  	 * device interrupts are disabled.
> > > > +	 * All modeset locks are held while the hook is called.
> > > >  	 */
> > > >  	void (*suspend)(struct intel_encoder *);
> > > > +	/*
> > > > +	 * Called without the modeset locks held after the suspend() hook for
> > > > +	 * all encoders have been called.
> > > > +	 */
> > > > +	void (*suspend_complete)(struct intel_encoder *encoder);
> > > >  	/*
> > > >  	 * Called during system reboot/shutdown after all the
> > > >  	 * encoders have been disabled and suspended.
> > > > +	 * All modeset locks are held while the hook is called.
> > > >  	 */
> > > >  	void (*shutdown)(struct intel_encoder *encoder);
> > > > +	/*
> > > > +	 * Called without the modeset locks held after the shutdown() hook for
> > > > +	 * all encoders have been called.
> > > > +	 */
> > > > +	void (*shutdown_complete)(struct intel_encoder *encoder);
> > > >  	/*
> > > >  	 * Enable/disable the clock to the port.
> > > >  	 */
> > > > diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
> > > > index fd198700272b1..705ba65f2ff9a 100644
> > > > --- a/drivers/gpu/drm/i915/i915_driver.c
> > > > +++ b/drivers/gpu/drm/i915/i915_driver.c
> > > > @@ -964,6 +964,10 @@ static void intel_suspend_encoders(struct drm_i915_private *dev_priv)
> > > >  		if (encoder->suspend)
> > > >  			encoder->suspend(encoder);
> > > >  	drm_modeset_unlock_all(&dev_priv->drm);
> > > > +
> > > > +	for_each_intel_encoder(&dev_priv->drm, encoder)
> > > > +		if (encoder->suspend_complete)
> > > > +			encoder->suspend_complete(encoder);
> > > >  }
> > > >  
> > > >  static void intel_shutdown_encoders(struct drm_i915_private *dev_priv)
> > > > @@ -978,6 +982,10 @@ static void intel_shutdown_encoders(struct drm_i915_private *dev_priv)
> > > >  		if (encoder->shutdown)
> > > >  			encoder->shutdown(encoder);
> > > >  	drm_modeset_unlock_all(&dev_priv->drm);
> > > > +
> > > > +	for_each_intel_encoder(&dev_priv->drm, encoder)
> > > > +		if (encoder->shutdown_complete)
> > > > +			encoder->shutdown_complete(encoder);
> > > >  }
> > > >  
> > > >  void i915_driver_shutdown(struct drm_i915_private *i915)
> > > > -- 
> > > > 2.37.2
> > > 
> > > -- 
> > > Ville Syrjälä
> > > Intel
> 
> -- 
> Ville Syrjälä
> Intel