[Intel-gfx] [PATCH] drm/i915/ehl: Add support for DPLL4 (v2)

[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.

Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy at intel.com>
Reviewed-by: Bob Paauwe <bob.j.paauwe at intel.com>
---
 drivers/gpu/drm/i915/intel_dpll_mgr.c | 60 ++++++++++++++++++++++++++++++++++-
 1 file changed, 59 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index e01c057ce50b..cb756acedc94 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -2870,6 +2870,56 @@ icl_get_dpll(struct intel_crtc_state *crtc_state,
 	return pll;
 }
 
+static struct intel_shared_dpll *
+ehl_get_dpll(struct intel_crtc_state *crtc_state,
+	     struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
+	struct intel_shared_dpll *pll;
+	enum port port = encoder->port;
+	enum intel_dpll_id min, max;
+	bool ret;
+
+	if (!intel_port_is_combophy(dev_priv, port)) {
+		MISSING_CASE(port);
+		return NULL;
+	}
+
+	min = DPLL_ID_ICL_DPLL0;
+	max = DPLL_ID_ICL_DPLL1;
+	ret = icl_calc_dpll_state(crtc_state, encoder);
+	if (ret) {
+		pll = intel_find_shared_dpll(crtc_state, min, max);
+		if (pll) {
+			intel_reference_shared_dpll(pll, crtc_state);
+			return pll;
+		}
+	} else {
+		DRM_DEBUG_KMS("Could not calculate PLL state.\n");
+	}
+
+	if (encoder->type == INTEL_OUTPUT_EDP) {
+		DRM_DEBUG_KMS("Cannot use DPLL4 with EDP.\n");
+		return NULL;
+	}
+
+	min = max = DPLL_ID_ICL_MGPLL1;
+	ret = icl_calc_mg_pll_state(crtc_state, false);
+	if (!ret) {
+		DRM_DEBUG_KMS("Could not calculate PLL state.\n");
+		return NULL;
+	}
+
+	pll = intel_find_shared_dpll(crtc_state, min, max);
+	if (!pll) {
+		DRM_DEBUG_KMS("No PLL selected\n");
+		return NULL;
+	}
+
+	intel_reference_shared_dpll(pll, crtc_state);
+	return pll;
+}
+
 static bool mg_pll_get_hw_state(struct drm_i915_private *dev_priv,
 				struct intel_shared_dpll *pll,
 				struct intel_dpll_hw_state *hw_state)
@@ -3115,6 +3165,13 @@ static void mg_pll_enable(struct drm_i915_private *dev_priv,
 	i915_reg_t enable_reg =
 		MG_PLL_ENABLE(icl_pll_id_to_tc_port(pll->info->id));
 
+	if (IS_ELKHARTLAKE(dev_priv) &&
+	   (I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC5 ||
+	    I915_READ(DC_STATE_EN) & DC_STATE_EN_UPTO_DC6)) {
+		DRM_ERROR("Cant enable DPLL4 when DC5 or DC6 are enabled\n");
+		return;
+	}
+
 	icl_pll_power_enable(dev_priv, pll, enable_reg);
 
 	icl_mg_pll_write(dev_priv, pll);
@@ -3249,12 +3306,13 @@ 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", &mg_pll_funcs, DPLL_ID_ICL_MGPLL1,0 },
 	{ },
 };
 
 static const struct intel_dpll_mgr ehl_pll_mgr = {
 	.dpll_info = ehl_plls,
-	.get_dpll = icl_get_dpll,
+	.get_dpll = ehl_get_dpll,
 	.dump_hw_state = icl_dump_hw_state,
 };
 
-- 
2.14.5