Re: [Intel-gfx] [PATCH v3 7/9] drm/i915: Factor out function to get/put AUX_IO power for main link

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

On Tue, Nov 08, 2022 at 05:18:26PM +0200, Imre Deak wrote:
> Factor out functions to get/put the AUX_IO power domain for the main
> link on DDI ports.
> 
> While at it clarify the corresponding code comment.
> 
> No functional change.
> 
> v2:
> - s/(get/put)_aux_power_for_main_link/main_link_aux_power_domain_(get/put)
>   (Jani)
> - Clarify in the code comment that AUX_IO is needed only by TypeC besides
>   eDP/PSR.
> v3:
> - Rebased on checking intel_encoder_can_psr() instead of crtc->has_psr.
> 
> Cc: Jani Nikula <jani.nikula@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 | 84 ++++++++++++++----------
>  1 file changed, 51 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index a087609223c60..21f1a68a57598 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -846,26 +846,63 @@ bool intel_ddi_get_hw_state(struct intel_encoder *encoder,
>  }
>  
>  static enum intel_display_power_domain
> -intel_ddi_main_link_aux_domain(struct intel_digital_port *dig_port)
> +intel_ddi_main_link_aux_domain(struct intel_digital_port *dig_port,
> +			       const struct intel_crtc_state *crtc_state)
>  {
>  	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> +	enum phy phy = intel_port_to_phy(i915, dig_port->base.port);
>  
> -	/* ICL+ HW requires corresponding AUX IOs to be powered up for PSR with
> +	/*
> +	 * ICL+ HW requires corresponding AUX IOs to be powered up for PSR with
>  	 * DC states enabled at the same time, while for driver initiated AUX
>  	 * transfers we need the same AUX IOs to be powered but with DC states
> -	 * disabled. Accordingly use the AUX power domain here which leaves DC
> -	 * states enabled.
> -	 * However, for non-A AUX ports the corresponding non-EDP transcoders
> -	 * would have already enabled power well 2 and DC_OFF. This means we can
> -	 * acquire a wider POWER_DOMAIN_AUX_{B,C,D,F} reference instead of a
> -	 * specific AUX_IO reference without powering up any extra wells.
> -	 * Note that PSR is enabled only on Port A even though this function
> -	 * returns the correct domain for other ports too.
> +	 * disabled. Accordingly use the AUX_IO_<port> power domain here which
> +	 * leaves DC states enabled.
> +	 *
> +	 * Before MTL TypeC PHYs (in all TypeC modes and both DP/HDMI) also require
> +	 * AUX IO to be enabled, but all these require DC_OFF to be enabled as
> +	 * well, so we can acquire a wider AUX_<port> power domain reference
> +	 * instead of a specific AUX_IO_<port> reference without powering up any
> +	 * extra wells.
>  	 */
>  	if (intel_encoder_can_psr(&dig_port->base))
>  		return intel_display_power_aux_io_domain(i915, dig_port->aux_ch);
> -	else
> +	else if (intel_crtc_has_dp_encoder(crtc_state) ||
> +		 intel_phy_is_tc(i915, phy))
>  		return intel_aux_power_domain(dig_port);
> +	else
> +		return POWER_DOMAIN_INVALID;
> +}
> +
> +static void
> +main_link_aux_power_domain_get(struct intel_digital_port *dig_port,
> +			       const struct intel_crtc_state *crtc_state)
> +{
> +	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> +	enum intel_display_power_domain domain =
> +		intel_ddi_main_link_aux_domain(dig_port, crtc_state);
> +
> +	drm_WARN_ON(&i915->drm, dig_port->aux_wakeref);
> +
> +	if (domain == POWER_DOMAIN_INVALID)
> +		return;
> +
> +	dig_port->aux_wakeref = intel_display_power_get(i915, domain);
> +}
> +
> +static void
> +main_link_aux_power_domain_put(struct intel_digital_port *dig_port,
> +			       const struct intel_crtc_state *crtc_state)
> +{
> +	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
> +	intel_wakeref_t wf = fetch_and_zero(&dig_port->aux_wakeref);

Please don't call functions with side effects in variable
declaration blocks. Far too easy to miss them and then you end up
scratching your head for a day or two debugging the wrong thing.

> +	enum intel_display_power_domain domain =
> +		intel_ddi_main_link_aux_domain(dig_port, crtc_state);
> +
> +	if (!wf)
> +		return;
> +
> +	intel_display_power_put(i915, domain, wf);
>  }
>  
>  static void intel_ddi_get_power_domains(struct intel_encoder *encoder,
> @@ -873,7 +910,6 @@ static void intel_ddi_get_power_domains(struct intel_encoder *encoder,
>  {
>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>  	struct intel_digital_port *dig_port;
> -	enum phy phy = intel_port_to_phy(dev_priv, encoder->port);
>  
>  	/*
>  	 * TODO: Add support for MST encoders. Atm, the following should never
> @@ -892,17 +928,7 @@ static void intel_ddi_get_power_domains(struct intel_encoder *encoder,
>  								   dig_port->ddi_io_power_domain);
>  	}
>  
> -	/*
> -	 * AUX power is only needed for (e)DP mode, and for HDMI mode on TC
> -	 * ports.
> -	 */
> -	if (intel_crtc_has_dp_encoder(crtc_state) ||
> -	    intel_phy_is_tc(dev_priv, phy)) {
> -		drm_WARN_ON(&dev_priv->drm, dig_port->aux_wakeref);
> -		dig_port->aux_wakeref =
> -			intel_display_power_get(dev_priv,
> -						intel_ddi_main_link_aux_domain(dig_port));
> -	}
> +	main_link_aux_power_domain_get(dig_port, crtc_state);
>  }
>  
>  void intel_ddi_enable_pipe_clock(struct intel_encoder *encoder,
> @@ -2741,10 +2767,7 @@ static void intel_ddi_post_disable(struct intel_atomic_state *state,
>  		intel_ddi_post_disable_dp(state, encoder, old_crtc_state,
>  					  old_conn_state);
>  
> -	if (intel_crtc_has_dp_encoder(old_crtc_state) || is_tc_port)
> -		intel_display_power_put(dev_priv,
> -					intel_ddi_main_link_aux_domain(dig_port),
> -					fetch_and_zero(&dig_port->aux_wakeref));
> +	main_link_aux_power_domain_put(dig_port, old_crtc_state);
>  
>  	if (is_tc_port)
>  		intel_tc_port_put_link(dig_port);
> @@ -3065,12 +3088,7 @@ intel_ddi_pre_pll_enable(struct intel_atomic_state *state,
>  	if (is_tc_port)
>  		intel_tc_port_get_link(dig_port, crtc_state->lane_count);
>  
> -	if (intel_crtc_has_dp_encoder(crtc_state) || is_tc_port) {
> -		drm_WARN_ON(&dev_priv->drm, dig_port->aux_wakeref);
> -		dig_port->aux_wakeref =
> -			intel_display_power_get(dev_priv,
> -						intel_ddi_main_link_aux_domain(dig_port));
> -	}
> +	main_link_aux_power_domain_get(dig_port, crtc_state);
>  
>  	if (is_tc_port && !intel_tc_port_in_tbt_alt_mode(dig_port))
>  		/*
> -- 
> 2.37.1

-- 
Ville Syrjälä
Intel