drm/i915/ltphy: Program LT Phy Non-TBT PLL disable sequence

Program in the steps for Non TBT PLL disable sequence.
The whole function can be defined in one shot since most of
prequiste functions are already coded in.

Bspec: 74492
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Link: https://patch.msgid.link/20251101032513.4171255-17-suraj.kandpal@intel.com

Author: surajk8

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

@@ -1627,3 +1627,81 @@ void intel_lt_phy_pll_enable(struct intel_encoder *encoder,
 
 	intel_lt_phy_transaction_end(encoder, wakeref);
 }
+
+void intel_lt_phy_pll_disable(struct intel_encoder *encoder)
+{
+	struct intel_display *display = to_intel_display(encoder);
+	enum phy phy = intel_encoder_to_phy(encoder);
+	enum port port = encoder->port;
+	intel_wakeref_t wakeref;
+	u8 owned_lane_mask = intel_lt_phy_get_owned_lane_mask(encoder);
+	u32 lane_pipe_reset = owned_lane_mask == INTEL_LT_PHY_BOTH_LANES
+				? (XELPDP_LANE_PIPE_RESET(0) |
+				   XELPDP_LANE_PIPE_RESET(1))
+				: XELPDP_LANE_PIPE_RESET(0);
+	u32 lane_phy_current_status = owned_lane_mask == INTEL_LT_PHY_BOTH_LANES
+					? (XELPDP_LANE_PHY_CURRENT_STATUS(0) |
+					   XELPDP_LANE_PHY_CURRENT_STATUS(1))
+					: XELPDP_LANE_PHY_CURRENT_STATUS(0);
+	u32 lane_phy_pulse_status = owned_lane_mask == INTEL_LT_PHY_BOTH_LANES
+					? (XE3PLPDP_LANE_PHY_PULSE_STATUS(0) |
+					   XE3PLPDP_LANE_PHY_PULSE_STATUS(1))
+					: XE3PLPDP_LANE_PHY_PULSE_STATUS(0);
+
+	wakeref = intel_lt_phy_transaction_begin(encoder);
+
+	/* 1. Clear PORT_BUF_CTL2 [PHY Pulse Status]. */
+	intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port),
+		     lane_phy_pulse_status,
+		     lane_phy_pulse_status);
+
+	/* 2. Set PORT_BUF_CTL2<port> Lane<PHY Lanes Owned> Pipe Reset to 1. */
+	intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port), lane_pipe_reset,
+		     lane_pipe_reset);
+
+	/* 3. Poll for PORT_BUF_CTL2<port> Lane<PHY Lanes Owned> PHY Current Status == 1. */
+	if (intel_de_wait_custom(display, XELPDP_PORT_BUF_CTL2(display, port),
+				 lane_phy_current_status,
+				 lane_phy_current_status,
+				 XE3PLPD_RESET_START_LATENCY_US, 0, NULL))
+		drm_warn(display->drm,
+			 "PHY %c failed to reset Lane after %dms.\n",
+			 phy_name(phy), XE3PLPD_RESET_START_LATENCY_US);
+
+	/* 4. Clear for PHY pulse status on owned PHY lanes. */
+	intel_de_rmw(display, XELPDP_PORT_BUF_CTL2(display, port),
+		     lane_phy_pulse_status,
+		     lane_phy_pulse_status);
+
+	/*
+	 * 5. Follow the Display Voltage Frequency Switching -
+	 * Sequence Before Frequency Change. We handle this step in bxt_set_cdclk().
+	 */
+	/* 6. Program PORT_CLOCK_CTL[PCLK PLL Request LN0] = 0. */
+	intel_de_rmw(display, XELPDP_PORT_CLOCK_CTL(display, port),
+		     XELPDP_LANE_PCLK_PLL_REQUEST(0), 0);
+
+	/* 7. Program DDI_CLK_VALFREQ to 0. */
+	intel_de_write(display, DDI_CLK_VALFREQ(encoder->port), 0);
+
+	/* 8. Poll for PORT_CLOCK_CTL[PCLK PLL Ack LN0]= 0. */
+	if (intel_de_wait_custom(display, XELPDP_PORT_CLOCK_CTL(display, port),
+				 XELPDP_LANE_PCLK_PLL_ACK(0), 0,
+				 XE3PLPD_MACCLK_TURNOFF_LATENCY_US, 0, NULL))
+		drm_warn(display->drm, "PHY %c PLL MacCLK Ack deassertion Timeout after %dus.\n",
+			 phy_name(phy), XE3PLPD_MACCLK_TURNOFF_LATENCY_US);
+
+	/*
+	 *  9. Follow the Display Voltage Frequency Switching -
+	 *  Sequence After Frequency Change. We handle this step in bxt_set_cdclk().
+	 */
+	/* 10. Program PORT_CLOCK_CTL register to disable and gate clocks. */
+	intel_de_rmw(display, XELPDP_PORT_CLOCK_CTL(display, port),
+		     XELPDP_DDI_CLOCK_SELECT_MASK(display) | XELPDP_FORWARD_CLOCK_UNGATE, 0);
+
+	/* 11. Program PORT_BUF_CTL5[MacCLK Reset_0] = 1 to assert MacCLK reset. */
+	intel_de_rmw(display, XE3PLPD_PORT_BUF_CTL5(port),
+		     XE3PLPD_MACCLK_RESET_0, XE3PLPD_MACCLK_RESET_0);
+
+	intel_lt_phy_transaction_end(encoder, wakeref);
+}

drivers/gpu/drm/i915/display/intel_lt_phy.h

@@ -14,6 +14,7 @@ struct intel_lt_phy_pll_state;
 
 void intel_lt_phy_pll_enable(struct intel_encoder *encoder,
 			     const struct intel_crtc_state *crtc_state);
+void intel_lt_phy_pll_disable(struct intel_encoder *encoder);
 int
 intel_lt_phy_pll_calc_state(struct intel_crtc_state *crtc_state,
 			    struct intel_encoder *encoder);

drivers/gpu/drm/i915/display/intel_lt_phy_regs.h

@@ -12,6 +12,7 @@
 #define XE3PLPD_MACCLK_TURNOFF_LATENCY_US	1
 #define XE3PLPD_RATE_CALIB_DONE_LATENCY_US	50
 #define XE3PLPD_RESET_START_LATENCY_US	10
+#define XE3PLPD_PWRDN_TO_RDY_LATENCY_US	4
 #define XE3PLPD_RESET_END_LATENCY_US		200
 
 /* LT Phy MAC Register */