drm/i915/ehl: Add support for DPLL4 (v10)

This patch adds support for DPLL4 on EHL that include the
following restrictions:

- DPLL4 cannot be used with DDIA (combo port A internal eDP usage).
  DPLL4 can be used with other DDIs, including DDID
  (combo port A external usage).

- DPLL4 cannot be enabled when DC5 or DC6 are enabled.

- The DPLL4 enable, lock, power enabled, and power state are connected
  to the MGPLL1_ENABLE register.

v2: (suggestions from Bob Paauwe)
- Rework ehl_get_dpll() function to call intel_find_shared_dpll() and
  iterate twice: once for Combo plls and once for MG plls.

- Use MG pll funcs for DPLL4 instead of creating new ones and modify
  mg_pll_enable to include the restrictions for EHL.

v3: Fix compilation error

v4: (suggestions from Lucas and Ville)
- Treat DPLL4 as a combo phy PLL and not as MG PLL
- Disable DC states when this DPLL is being enabled
- Reuse icl_get_dpll instead of creating a separate one for EHL

v5: (suggestion from Ville)
- Refcount the DC OFF power domains during the enabling and disabling
  of this DPLL.

v6: rebase

v7: (suggestion from Imre)
- Add a new power domain instead of iterating over the domains
  assoicated with DC OFF power well.

v8: (Ville and Imre)
- Rename POWER_DOMAIN_DPLL4 TO POWER_DOMAIN_DPLL_DC_OFF
- Grab a reference in intel_modeset_setup_hw_state() if this
  DPLL was already enabled perhaps by BIOS.
- Check for the port type instead of the encoder

v9: (Ville)
- Move the block of code that grabs a reference to the power domain
  POWER_DOMAIN_DPLL_DC_OFF to intel_modeset_readout_hw_state() to ensure
  that there is a reference present before this DPLL might get disabled.

v10: rebase

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190703230353.24059-1-vivek.kasireddy@intel.com

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

@@ -16675,6 +16675,13 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
 
 		pll->on = pll->info->funcs->get_hw_state(dev_priv, pll,
 							&pll->state.hw_state);
+
+		if (IS_ELKHARTLAKE(dev_priv) && pll->on &&
+		    pll->info->id == DPLL_ID_EHL_DPLL4) {
+			pll->wakeref = intel_display_power_get(dev_priv,
+							       POWER_DOMAIN_DPLL_DC_OFF);
+		}
+
 		pll->state.crtc_mask = 0;
 		for_each_intel_crtc(dev, crtc) {
 			struct intel_crtc_state *crtc_state =

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

@@ -118,6 +118,8 @@ intel_display_power_domain_str(enum intel_display_power_domain domain)
 		return "MODESET";
 	case POWER_DOMAIN_GT_IRQ:
 		return "GT_IRQ";
+	case POWER_DOMAIN_DPLL_DC_OFF:
+		return "DPLL_DC_OFF";
 	default:
 		MISSING_CASE(domain);
 		return "?";
@@ -2455,6 +2457,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
 	ICL_PW_2_POWER_DOMAINS |			\
 	BIT_ULL(POWER_DOMAIN_MODESET) |			\
 	BIT_ULL(POWER_DOMAIN_AUX_A) |			\
+	BIT_ULL(POWER_DOMAIN_DPLL_DC_OFF) |			\
 	BIT_ULL(POWER_DOMAIN_INIT))
 
 #define ICL_DDI_IO_A_POWER_DOMAINS (			\

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

@@ -59,6 +59,7 @@ enum intel_display_power_domain {
 	POWER_DOMAIN_GMBUS,
 	POWER_DOMAIN_MODESET,
 	POWER_DOMAIN_GT_IRQ,
+	POWER_DOMAIN_DPLL_DC_OFF,
 	POWER_DOMAIN_INIT,
 
 	POWER_DOMAIN_NUM,

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

@@ -2905,6 +2905,9 @@ static bool icl_get_combo_phy_dpll(struct intel_atomic_state *state,
 		intel_atomic_get_new_crtc_state(state, crtc);
 	struct icl_port_dpll *port_dpll =
 		&crtc_state->icl_port_dplls[ICL_PORT_DPLL_DEFAULT];
+	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	enum port port = encoder->port;
+	bool has_dpll4 = false;
 
 	if (!icl_calc_dpll_state(crtc_state, encoder, &port_dpll->hw_state)) {
 		DRM_DEBUG_KMS("Could not calculate combo PHY PLL state.\n");
@@ -2912,10 +2915,14 @@ static bool icl_get_combo_phy_dpll(struct intel_atomic_state *state,
 		return false;
 	}
 
+	if (IS_ELKHARTLAKE(dev_priv) && port != PORT_A)
+		has_dpll4 = true;
+
 	port_dpll->pll = intel_find_shared_dpll(state, crtc,
 						&port_dpll->hw_state,
 						DPLL_ID_ICL_DPLL0,
-						DPLL_ID_ICL_DPLL1);
+						has_dpll4 ? DPLL_ID_EHL_DPLL4
+							  : DPLL_ID_ICL_DPLL1);
 	if (!port_dpll->pll) {
 		DRM_DEBUG_KMS("No combo PHY PLL found for port %c\n",
 			      port_name(encoder->port));
@@ -3119,8 +3126,14 @@ static bool combo_pll_get_hw_state(struct drm_i915_private *dev_priv,
 				   struct intel_shared_dpll *pll,
 				   struct intel_dpll_hw_state *hw_state)
 {
-	return icl_pll_get_hw_state(dev_priv, pll, hw_state,
-				    CNL_DPLL_ENABLE(pll->info->id));
+	i915_reg_t enable_reg = CNL_DPLL_ENABLE(pll->info->id);
+
+	if (IS_ELKHARTLAKE(dev_priv) &&
+	    pll->info->id == DPLL_ID_EHL_DPLL4) {
+		enable_reg = MG_PLL_ENABLE(0);
+	}
+
+	return icl_pll_get_hw_state(dev_priv, pll, hw_state, enable_reg);
 }
 
 static bool tbt_pll_get_hw_state(struct drm_i915_private *dev_priv,
@@ -3231,6 +3244,19 @@ static void combo_pll_enable(struct drm_i915_private *dev_priv,
 {
 	i915_reg_t enable_reg = CNL_DPLL_ENABLE(pll->info->id);
 
+	if (IS_ELKHARTLAKE(dev_priv) &&
+	    pll->info->id == DPLL_ID_EHL_DPLL4) {
+		enable_reg = MG_PLL_ENABLE(0);
+
+		/*
+		 * We need to disable DC states when this DPLL is enabled.
+		 * This can be done by taking a reference on DPLL4 power
+		 * domain.
+		 */
+		pll->wakeref = intel_display_power_get(dev_priv,
+						       POWER_DOMAIN_DPLL_DC_OFF);
+	}
+
 	icl_pll_power_enable(dev_priv, pll, enable_reg);
 
 	icl_dpll_write(dev_priv, pll);
@@ -3326,7 +3352,19 @@ static void icl_pll_disable(struct drm_i915_private *dev_priv,
 static void combo_pll_disable(struct drm_i915_private *dev_priv,
 			      struct intel_shared_dpll *pll)
 {
-	icl_pll_disable(dev_priv, pll, CNL_DPLL_ENABLE(pll->info->id));
+	i915_reg_t enable_reg = CNL_DPLL_ENABLE(pll->info->id);
+
+	if (IS_ELKHARTLAKE(dev_priv) &&
+	    pll->info->id == DPLL_ID_EHL_DPLL4) {
+		enable_reg = MG_PLL_ENABLE(0);
+		icl_pll_disable(dev_priv, pll, enable_reg);
+
+		intel_display_power_put(dev_priv, POWER_DOMAIN_DPLL_DC_OFF,
+					pll->wakeref);
+		return;
+	}
+
+	icl_pll_disable(dev_priv, pll, enable_reg);
 }
 
 static void tbt_pll_disable(struct drm_i915_private *dev_priv,
@@ -3406,6 +3444,7 @@ static const struct intel_dpll_mgr icl_pll_mgr = {
 static const struct dpll_info ehl_plls[] = {
 	{ "DPLL 0", &combo_pll_funcs, DPLL_ID_ICL_DPLL0, 0 },
 	{ "DPLL 1", &combo_pll_funcs, DPLL_ID_ICL_DPLL1, 0 },
+	{ "DPLL 4", &combo_pll_funcs, DPLL_ID_EHL_DPLL4, 0 },
 	{ },
 };
 

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

@@ -28,6 +28,7 @@
 #include <linux/types.h>
 
 #include "intel_display.h"
+#include "intel_wakeref.h"
 
 /*FIXME: Move this to a more appropriate place. */
 #define abs_diff(a, b) ({			\
@@ -118,6 +119,10 @@ enum intel_dpll_id {
 	 * @DPLL_ID_ICL_DPLL1: ICL combo PHY DPLL1
 	 */
 	DPLL_ID_ICL_DPLL1 = 1,
+	/**
+	 * @DPLL_ID_EHL_DPLL4: EHL combo PHY DPLL4
+	 */
+	DPLL_ID_EHL_DPLL4 = 2,
 	/**
 	 * @DPLL_ID_ICL_TBTPLL: ICL TBT PLL
 	 */
@@ -320,6 +325,7 @@ struct intel_shared_dpll {
 	 * @info: platform specific info
 	 */
 	const struct dpll_info *info;
+	intel_wakeref_t wakeref;
 };
 
 #define SKL_DPLL0 0