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

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

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?

> 
> 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