drm/i915: Factor out function to get/put AUX_IO power for main link

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.
v4:
- Don't call fetch_and_zero() with side-effect during variable
  declaration. (Ville)

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221114122251.21327-9-imre.deak@intel.com

drivers/gpu/drm/i915/display/intel_ddi.c

@@ -848,26 +848,64 @@ 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);
+	enum intel_display_power_domain domain =
+		intel_ddi_main_link_aux_domain(dig_port, crtc_state);
+	intel_wakeref_t wf;
+
+	wf = fetch_and_zero(&dig_port->aux_wakeref);
+	if (!wf)
+		return;
+
+	intel_display_power_put(i915, domain, wf);
 }
 
 static void intel_ddi_get_power_domains(struct intel_encoder *encoder,
@@ -875,7 +913,6 @@ 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
@@ -894,17 +931,7 @@ 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,
@@ -2743,10 +2770,7 @@ 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);
@@ -3067,12 +3091,7 @@ 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))
 		/*