drm/i915/mtl: Reset only one lane in case of MFD

In case when only two or less transmit lanes are owned such as MFD
(DP-alt with x2 lanes) we need to reset only one data lane (lane0).
With only x2 lanes we don't need to poll for the phy current
status on both data lanes since only the owned data lane will respond.

v2: Find better naming for lanes and revise the commit message (Luca)

Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com> (v1)
Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com> (v2)
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230601101314.332392-1-mika.kahola@intel.com

drivers/gpu/drm/i915/display/intel_cx0_phy.c

@@ -2528,13 +2528,23 @@ static u32 intel_cx0_get_pclk_refclk_ack(u8 lane_mask)
 	return val;
 }
 
-/* FIXME: Some Type-C cases need not reset both the lanes. Handle those cases. */
-static void intel_cx0_phy_lane_reset(struct drm_i915_private *i915, enum port port,
+static void intel_cx0_phy_lane_reset(struct drm_i915_private *i915,
+				     struct intel_encoder *encoder,
 				     bool lane_reversal)
 {
+	enum port port = encoder->port;
 	enum phy phy = intel_port_to_phy(i915, port);
+	bool both_lanes =  intel_tc_port_fia_max_lane_count(enc_to_dig_port(encoder)) > 2;
 	u8 lane_mask = lane_reversal ? INTEL_CX0_LANE1 :
 				  INTEL_CX0_LANE0;
+	u32 lane_pipe_reset = both_lanes ?
+			      XELPDP_LANE_PIPE_RESET(0) |
+			      XELPDP_LANE_PIPE_RESET(1) :
+			      XELPDP_LANE_PIPE_RESET(0);
+	u32 lane_phy_current_status = both_lanes ?
+				      XELPDP_LANE_PHY_CURRENT_STATUS(0) |
+				      XELPDP_LANE_PHY_CURRENT_STATUS(1) :
+				      XELPDP_LANE_PHY_CURRENT_STATUS(0);
 
 	if (__intel_de_wait_for_register(i915, XELPDP_PORT_BUF_CTL1(port),
 					 XELPDP_PORT_BUF_SOC_PHY_READY,
@@ -2545,23 +2555,24 @@ static void intel_cx0_phy_lane_reset(struct drm_i915_private *i915, enum port po
 
 	intel_de_rmw(i915, XELPDP_PORT_BUF_CTL2(port),
 		     XELPDP_LANE_PIPE_RESET(0) | XELPDP_LANE_PIPE_RESET(1),
-		     XELPDP_LANE_PIPE_RESET(0) | XELPDP_LANE_PIPE_RESET(1));
+		     lane_pipe_reset);
 
 	if (__intel_de_wait_for_register(i915, XELPDP_PORT_BUF_CTL2(port),
-					 XELPDP_LANE_PHY_CURRENT_STATUS(0) |
-					 XELPDP_LANE_PHY_CURRENT_STATUS(1),
-					 XELPDP_LANE_PHY_CURRENT_STATUS(0) |
-					 XELPDP_LANE_PHY_CURRENT_STATUS(1),
+					 lane_phy_current_status, lane_phy_current_status,
 					 XELPDP_PORT_RESET_START_TIMEOUT_US, 0, NULL))
 		drm_warn(&i915->drm, "PHY %c failed to bring out of Lane reset after %dus.\n",
 			 phy_name(phy), XELPDP_PORT_RESET_START_TIMEOUT_US);
 
 	intel_de_rmw(i915, XELPDP_PORT_CLOCK_CTL(port),
-		     intel_cx0_get_pclk_refclk_request(INTEL_CX0_BOTH_LANES),
+		     intel_cx0_get_pclk_refclk_request(both_lanes ?
+						       INTEL_CX0_BOTH_LANES :
+						       INTEL_CX0_LANE0),
 		     intel_cx0_get_pclk_refclk_request(lane_mask));
 
 	if (__intel_de_wait_for_register(i915, XELPDP_PORT_CLOCK_CTL(port),
-					 intel_cx0_get_pclk_refclk_ack(INTEL_CX0_BOTH_LANES),
+					 intel_cx0_get_pclk_refclk_ack(both_lanes ?
+								       INTEL_CX0_BOTH_LANES :
+								       INTEL_CX0_LANE0),
 					 intel_cx0_get_pclk_refclk_ack(lane_mask),
 					 XELPDP_REFCLK_ENABLE_TIMEOUT_US, 0, NULL))
 		drm_warn(&i915->drm, "PHY %c failed to request refclk after %dus.\n",
@@ -2571,13 +2582,9 @@ static void intel_cx0_phy_lane_reset(struct drm_i915_private *i915, enum port po
 					    CX0_P2_STATE_RESET);
 	intel_cx0_setup_powerdown(i915, port);
 
-	intel_de_rmw(i915, XELPDP_PORT_BUF_CTL2(port),
-		     XELPDP_LANE_PIPE_RESET(0) | XELPDP_LANE_PIPE_RESET(1),
-		     0);
+	intel_de_rmw(i915, XELPDP_PORT_BUF_CTL2(port), lane_pipe_reset, 0);
 
-	if (intel_de_wait_for_clear(i915, XELPDP_PORT_BUF_CTL2(port),
-				    XELPDP_LANE_PHY_CURRENT_STATUS(0) |
-				    XELPDP_LANE_PHY_CURRENT_STATUS(1),
+	if (intel_de_wait_for_clear(i915, XELPDP_PORT_BUF_CTL2(port), lane_phy_current_status,
 				    XELPDP_PORT_RESET_END_TIMEOUT))
 		drm_warn(&i915->drm, "PHY %c failed to bring out of Lane reset after %dms.\n",
 			 phy_name(phy), XELPDP_PORT_RESET_END_TIMEOUT);
@@ -2705,7 +2712,7 @@ static void intel_cx0pll_enable(struct intel_encoder *encoder,
 	intel_program_port_clock_ctl(encoder, crtc_state, lane_reversal);
 
 	/* 2. Bring PHY out of reset. */
-	intel_cx0_phy_lane_reset(i915, encoder->port, lane_reversal);
+	intel_cx0_phy_lane_reset(i915, encoder, lane_reversal);
 
 	/*
 	 * 3. Change Phy power state to Ready.