[PATCH v2 1/2] drm/i915: Allow /2 CD2X divider on gen11+

[Matt Roper <matthew.d.roper@intel.com>]

The bspec has just recently been updated with new cdclk values that
require the use of a /2 CD2X divider rather than a /1 divider.  Once we
add the divider selection logic to ICL+ cdclk programming, we have
pretty much the same logic we were already using on CNL, so it's simpler
to drop icl_set_cdclk() completely and reuse cnl_set_cdclk() on gen11+
platforms as well.

v2:
 - Using ICL_CDCLK_CD2X_PIPE_NONE + BXT_CDCLK_CD2X_PIPE(pipe) for TGL is
   correct, but looks really confusing.  Add some TGL_ macros that alias
   these to avoid confusion.  (Ville)
 - Use DIV_ROUND_CLOSEST rather than / when applying the divider. (Ville)

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
Unifying the get_cdclk functions too might be worth looking into in the
future, but it wasn't as straightforward as the set_cdclk functions so
I'm not going to tackle that with this series.

 drivers/gpu/drm/i915/display/intel_cdclk.c | 90 +++++++++-------------
 drivers/gpu/drm/i915/i915_reg.h            |  3 +
 2 files changed, 38 insertions(+), 55 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 939088c7d814..58ba42dcf23f 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -1659,10 +1659,23 @@ static void cnl_set_cdclk(struct drm_i915_private *dev_priv,
 		cnl_cdclk_pll_enable(dev_priv, vco);
 
 	val = divider | skl_cdclk_decimal(cdclk);
-	if (pipe == INVALID_PIPE)
-		val |= BXT_CDCLK_CD2X_PIPE_NONE;
-	else
-		val |= BXT_CDCLK_CD2X_PIPE(pipe);
+
+	if (INTEL_GEN(dev_priv) >= 12) {
+		if (pipe == INVALID_PIPE)
+			val |= TGL_CDCLK_CD2X_PIPE_NONE;
+		else
+			val |= TGL_CDCLK_CD2X_PIPE(pipe);
+	} else if (INTEL_GEN(dev_priv) >= 11) {
+		if (pipe == INVALID_PIPE)
+			val |= ICL_CDCLK_CD2X_PIPE_NONE;
+		else
+			val |= ICL_CDCLK_CD2X_PIPE(pipe);
+	} else {
+		if (pipe == INVALID_PIPE)
+			val |= BXT_CDCLK_CD2X_PIPE_NONE;
+		else
+			val |= BXT_CDCLK_CD2X_PIPE(pipe);
+	}
 	I915_WRITE(CDCLK_CTL, val);
 
 	if (pipe != INVALID_PIPE)
@@ -1813,51 +1826,6 @@ static int icl_calc_cdclk_pll_vco(struct drm_i915_private *dev_priv, int cdclk)
 	return dev_priv->cdclk.hw.ref * ratio;
 }
 
-static void icl_set_cdclk(struct drm_i915_private *dev_priv,
-			  const struct intel_cdclk_state *cdclk_state,
-			  enum pipe pipe)
-{
-	unsigned int cdclk = cdclk_state->cdclk;
-	unsigned int vco = cdclk_state->vco;
-	int ret;
-
-	ret = skl_pcode_request(dev_priv, SKL_PCODE_CDCLK_CONTROL,
-				SKL_CDCLK_PREPARE_FOR_CHANGE,
-				SKL_CDCLK_READY_FOR_CHANGE,
-				SKL_CDCLK_READY_FOR_CHANGE, 3);
-	if (ret) {
-		DRM_ERROR("Failed to inform PCU about cdclk change (%d)\n",
-			  ret);
-		return;
-	}
-
-	if (dev_priv->cdclk.hw.vco != 0 &&
-	    dev_priv->cdclk.hw.vco != vco)
-		cnl_cdclk_pll_disable(dev_priv);
-
-	if (dev_priv->cdclk.hw.vco != vco)
-		cnl_cdclk_pll_enable(dev_priv, vco);
-
-	/*
-	 * On ICL CD2X_DIV can only be 1, so we'll never end up changing the
-	 * divider here synchronized to a pipe while CDCLK is on, nor will we
-	 * need the corresponding vblank wait.
-	 */
-	I915_WRITE(CDCLK_CTL, ICL_CDCLK_CD2X_PIPE_NONE |
-			      skl_cdclk_decimal(cdclk));
-
-	sandybridge_pcode_write(dev_priv, SKL_PCODE_CDCLK_CONTROL,
-				cdclk_state->voltage_level);
-
-	intel_update_cdclk(dev_priv);
-
-	/*
-	 * Can't read out the voltage level :(
-	 * Let's just assume everything is as expected.
-	 */
-	dev_priv->cdclk.hw.voltage_level = cdclk_state->voltage_level;
-}
-
 static u8 icl_calc_voltage_level(struct drm_i915_private *dev_priv, int cdclk)
 {
 	if (IS_ELKHARTLAKE(dev_priv)) {
@@ -1881,6 +1849,7 @@ static void icl_get_cdclk(struct drm_i915_private *dev_priv,
 			  struct intel_cdclk_state *cdclk_state)
 {
 	u32 val;
+	int div;
 
 	cdclk_state->bypass = 50000;
 
@@ -1914,10 +1883,21 @@ static void icl_get_cdclk(struct drm_i915_private *dev_priv,
 
 	cdclk_state->vco = (val & BXT_DE_PLL_RATIO_MASK) * cdclk_state->ref;
 
-	val = I915_READ(CDCLK_CTL);
-	WARN_ON((val & BXT_CDCLK_CD2X_DIV_SEL_MASK) != 0);
+	val = I915_READ(CDCLK_CTL) & BXT_CDCLK_CD2X_DIV_SEL_MASK;
+	switch (val) {
+	case BXT_CDCLK_CD2X_DIV_SEL_1:
+		div = 2;
+		break;
+	case BXT_CDCLK_CD2X_DIV_SEL_2:
+		div = 4;
+		break;
+	default:
+		MISSING_CASE(val);
+		div = 2;
+		break;
+	}
 
-	cdclk_state->cdclk = cdclk_state->vco / 2;
+	cdclk_state->cdclk = DIV_ROUND_CLOSEST(cdclk_state->vco, div);
 
 out:
 	/*
@@ -1963,7 +1943,7 @@ static void icl_init_cdclk(struct drm_i915_private *dev_priv)
 				icl_calc_voltage_level(dev_priv,
 						       sanitized_state.cdclk);
 
-	icl_set_cdclk(dev_priv, &sanitized_state, INVALID_PIPE);
+	cnl_set_cdclk(dev_priv, &sanitized_state, INVALID_PIPE);
 }
 
 static void icl_uninit_cdclk(struct drm_i915_private *dev_priv)
@@ -1975,7 +1955,7 @@ static void icl_uninit_cdclk(struct drm_i915_private *dev_priv)
 	cdclk_state.voltage_level = icl_calc_voltage_level(dev_priv,
 							   cdclk_state.cdclk);
 
-	icl_set_cdclk(dev_priv, &cdclk_state, INVALID_PIPE);
+	cnl_set_cdclk(dev_priv, &cdclk_state, INVALID_PIPE);
 }
 
 static void cnl_init_cdclk(struct drm_i915_private *dev_priv)
@@ -2810,7 +2790,7 @@ void intel_update_rawclk(struct drm_i915_private *dev_priv)
 void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv)
 {
 	if (INTEL_GEN(dev_priv) >= 11) {
-		dev_priv->display.set_cdclk = icl_set_cdclk;
+		dev_priv->display.set_cdclk = cnl_set_cdclk;
 		dev_priv->display.modeset_calc_cdclk = icl_modeset_calc_cdclk;
 	} else if (IS_CANNONLAKE(dev_priv)) {
 		dev_priv->display.set_cdclk = cnl_set_cdclk;
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index a142aa3d74e3..c47e2969ad04 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -9671,7 +9671,10 @@ enum skl_power_gate {
 #define  BXT_CDCLK_CD2X_PIPE(pipe)	((pipe) << 20)
 #define  CDCLK_DIVMUX_CD_OVERRIDE	(1 << 19)
 #define  BXT_CDCLK_CD2X_PIPE_NONE	BXT_CDCLK_CD2X_PIPE(3)
+#define  ICL_CDCLK_CD2X_PIPE(pipe)	(_PICK(pipe, 0, 2, 6) << 19)
 #define  ICL_CDCLK_CD2X_PIPE_NONE	(7 << 19)
+#define  TGL_CDCLK_CD2X_PIPE(pipe)	BXT_CDCLK_CD2X_PIPE(pipe)
+#define  TGL_CDCLK_CD2X_PIPE_NONE	ICL_CDCLK_CD2X_PIPE_NONE
 #define  BXT_CDCLK_SSA_PRECHARGE_ENABLE	(1 << 16)
 #define  CDCLK_FREQ_DECIMAL_MASK	(0x7ff)
 
-- 
2.20.1

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