drm/i915/tc: Add asserts in TC PHY hooks that the required power is on

Add an assert to each TC PHY hook that their required power domain is
enabled.

While at it add a comment describing the domains used on each platform
and TC mode.

v2: Fix non kernel-doc multiline comments. (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230323142035.1432621-21-imre.deak@intel.com

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

@@ -111,6 +111,46 @@ bool intel_tc_port_in_legacy_mode(struct intel_digital_port *dig_port)
 	return intel_tc_port_in_mode(dig_port, TC_PORT_LEGACY);
 }
 
+/*
+ * The display power domains used for TC ports depending on the
+ * platform and TC mode (legacy, DP-alt, TBT):
+ *
+ * POWER_DOMAIN_DISPLAY_CORE:
+ * --------------------------
+ * ADLP/all modes:
+ *   - TCSS/IOM access for PHY ready state.
+ * ADLP+/all modes:
+ *   - DE/north-,south-HPD ISR access for HPD live state.
+ *
+ * POWER_DOMAIN_PORT_DDI_LANES_<port>:
+ * -----------------------------------
+ * ICL+/all modes:
+ *   - DE/DDI_BUF access for port enabled state.
+ * ADLP/all modes:
+ *   - DE/DDI_BUF access for PHY owned state.
+ *
+ * POWER_DOMAIN_AUX_USBC<TC port index>:
+ * -------------------------------------
+ * ICL/legacy mode:
+ *   - TCSS/IOM,FIA access for PHY ready, owned and HPD live state
+ *   - TCSS/PHY: block TC-cold power state for using the PHY AUX and
+ *     main lanes.
+ * ADLP/legacy, DP-alt modes:
+ *   - TCSS/PHY: block TC-cold power state for using the PHY AUX and
+ *     main lanes.
+ *
+ * POWER_DOMAIN_TC_COLD_OFF:
+ * -------------------------
+ * TGL/legacy, DP-alt modes:
+ *   - TCSS/IOM,FIA access for PHY ready, owned and HPD live state
+ *   - TCSS/PHY: block TC-cold power state for using the PHY AUX and
+ *     main lanes.
+ *
+ * ICL, TGL, ADLP/TBT mode:
+ *   - TCSS/IOM,FIA access for HPD live state
+ *   - TCSS/TBT: block TC-cold power state for using the (TBT DP-IN)
+ *     AUX and main lanes.
+ */
 bool intel_tc_cold_requires_aux_pw(struct intel_digital_port *dig_port)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
@@ -163,6 +203,15 @@ tc_cold_unblock(struct intel_tc_port *tc, intel_wakeref_t wakeref)
 	__tc_cold_unblock(tc, domain, wakeref);
 }
 
+static void
+assert_display_core_power_enabled(struct intel_tc_port *tc)
+{
+	struct drm_i915_private *i915 = tc_to_i915(tc);
+
+	drm_WARN_ON(&i915->drm,
+		    !intel_display_power_is_enabled(i915, POWER_DOMAIN_DISPLAY_CORE));
+}
+
 static void
 assert_tc_cold_blocked(struct intel_tc_port *tc)
 {
@@ -378,6 +427,8 @@ static bool icl_tc_phy_is_ready(struct intel_tc_port *tc)
 	struct drm_i915_private *i915 = tc_to_i915(tc);
 	u32 val;
 
+	assert_tc_cold_blocked(tc);
+
 	val = intel_de_read(i915, PORT_TX_DFLEXDPPMS(tc->phy_fia));
 	if (val == 0xffffffff) {
 		drm_dbg_kms(&i915->drm,
@@ -395,6 +446,8 @@ static bool icl_tc_phy_take_ownership(struct intel_tc_port *tc,
 	struct drm_i915_private *i915 = tc_to_i915(tc);
 	u32 val;
 
+	assert_tc_cold_blocked(tc);
+
 	val = intel_de_read(i915, PORT_TX_DFLEXDPCSSS(tc->phy_fia));
 	if (val == 0xffffffff) {
 		drm_dbg_kms(&i915->drm,
@@ -418,6 +471,8 @@ static bool icl_tc_phy_is_owned(struct intel_tc_port *tc)
 	struct drm_i915_private *i915 = tc_to_i915(tc);
 	u32 val;
 
+	assert_tc_cold_blocked(tc);
+
 	val = intel_de_read(i915, PORT_TX_DFLEXDPCSSS(tc->phy_fia));
 	if (val == 0xffffffff) {
 		drm_dbg_kms(&i915->drm,
@@ -626,6 +681,8 @@ static bool adlp_tc_phy_is_ready(struct intel_tc_port *tc)
 	enum tc_port tc_port = intel_port_to_tc(i915, tc->dig_port->base.port);
 	u32 val;
 
+	assert_display_core_power_enabled(tc);
+
 	val = intel_de_read(i915, TCSS_DDI_STATUS(tc_port));
 	if (val == 0xffffffff) {
 		drm_dbg_kms(&i915->drm,
@@ -643,6 +700,8 @@ static bool adlp_tc_phy_take_ownership(struct intel_tc_port *tc,
 	struct drm_i915_private *i915 = tc_to_i915(tc);
 	enum port port = tc->dig_port->base.port;
 
+	assert_tc_port_power_enabled(tc);
+
 	intel_de_rmw(i915, DDI_BUF_CTL(port), DDI_BUF_CTL_TC_PHY_OWNERSHIP,
 		     take ? DDI_BUF_CTL_TC_PHY_OWNERSHIP : 0);
 
@@ -655,6 +714,8 @@ static bool adlp_tc_phy_is_owned(struct intel_tc_port *tc)
 	enum port port = tc->dig_port->base.port;
 	u32 val;
 
+	assert_tc_port_power_enabled(tc);
+
 	val = intel_de_read(i915, DDI_BUF_CTL(port));
 	return val & DDI_BUF_CTL_TC_PHY_OWNERSHIP;
 }