[PATCH] drm/i915/ehl: Add support for DPLL4 (v8)

[Vivek Kasireddy <vivek.kasireddy@intel.com>]

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

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>
---
 drivers/gpu/drm/i915/display/intel_display.c  |  6 +++
 .../drm/i915/display/intel_display_power.c    |  3 ++
 .../drm/i915/display/intel_display_power.h    |  1 +
 drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 42 +++++++++++++++++--
 drivers/gpu/drm/i915/display/intel_dpll_mgr.h |  6 +++
 5 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 8592a7d422de..a5f387e486ee 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -16778,6 +16778,12 @@ intel_modeset_setup_hw_state(struct drm_device *dev,
 	for (i = 0; i < dev_priv->num_shared_dpll; i++) {
 		struct intel_shared_dpll *pll = &dev_priv->shared_dplls[i];
 
+		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);
+		}
+
 		if (!pll->on || pll->active_mask)
 			continue;
 
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index c93ad512014c..1c101a842331 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -117,6 +117,8 @@ 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 "?";
@@ -2361,6 +2363,7 @@ 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 (			\
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index ff57b0a7fe59..8f43f7051a16 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/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,
diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
index 2d4e7b9a7b9d..81e1443cb583 100644
--- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
@@ -2806,6 +2806,10 @@ icl_get_dpll(struct intel_crtc_state *crtc_state,
 	if (intel_port_is_combophy(dev_priv, port)) {
 		min = DPLL_ID_ICL_DPLL0;
 		max = DPLL_ID_ICL_DPLL1;
+
+		if (IS_ELKHARTLAKE(dev_priv) && port != PORT_A)
+			max = DPLL_ID_EHL_DPLL4;
+
 		ret = icl_calc_dpll_state(crtc_state, encoder);
 	} else if (intel_port_is_tc(dev_priv, port)) {
 		if (encoder->type == INTEL_OUTPUT_DP_MST) {
@@ -2945,8 +2949,14 @@ 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,
@@ -3057,6 +3067,19 @@ 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);
@@ -3152,7 +3175,19 @@ 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,
@@ -3230,6 +3265,7 @@ 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 },
 	{ },
 };
 
diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.h b/drivers/gpu/drm/i915/display/intel_dpll_mgr.h
index d0570414f3d1..3e2aa1099562 100644
--- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.h
+++ b/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) ({			\
@@ -117,6 +118,10 @@ 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
 	 */
@@ -312,6 +317,7 @@ struct intel_shared_dpll {
 	 * @info: platform specific info
 	 */
 	const struct dpll_info *info;
+	intel_wakeref_t wakeref;
 };
 
 #define SKL_DPLL0 0
-- 
2.21.0

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