[Intel-gfx] [PATCH] drm/i915/ehl: Add support for DPLL4 (v4)

[Vivek Kasireddy]

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

Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Cc: Bob Paauwe <bob.j.paauwe at intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy at intel.com>
---
 drivers/gpu/drm/i915/intel_dpll_mgr.c | 35 ++++++++++++++++++++++++++++++++---
 drivers/gpu/drm/i915/intel_dpll_mgr.h |  4 ++++
 2 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index e01c057ce50b..207af4af4978 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -2825,6 +2825,12 @@ 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)) {
+			if (encoder->type != INTEL_OUTPUT_EDP)
+				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) {
@@ -2964,8 +2970,14 @@ 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,
@@ -3076,6 +3088,14 @@ 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);
+
+		/* Need to disable DC states when this DPLL is enabled. */
+		bxt_disable_dc9(dev_priv);
+	}
+
 	icl_pll_power_enable(dev_priv, pll, enable_reg);
 
 	icl_dpll_write(dev_priv, pll);
@@ -3171,7 +3191,15 @@ 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);
+		bxt_enable_dc9(dev_priv);
+	}
+
+	icl_pll_disable(dev_priv, pll, enable_reg);
 }
 
 static void tbt_pll_disable(struct drm_i915_private *dev_priv,
@@ -3249,6 +3277,7 @@ 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/intel_dpll_mgr.h b/drivers/gpu/drm/i915/intel_dpll_mgr.h
index bd8124cc81ed..f3f99929cee8 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.h
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.h
@@ -113,6 +113,10 @@ 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
 	 */
-- 
2.14.5