drm/i915/display: Set correct voltage level for 480MHz CDCLK

According to Bspec, the voltage level for 480MHz is to be set as 1
instead of 2.

BSpec: 49208

Fixes: 06f1b06d ("drm/i915/display: Add 480 MHz CDCLK steps for RPL-U")

v2: rebase
Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230529060747.3972259-1-chaitanya.kumar.borah@intel.com
(cherry picked from commit 5a3c46b8)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

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

@@ -1453,6 +1453,18 @@ static u8 tgl_calc_voltage_level(int cdclk)
 		return 0;
 }
 
+static u8 rplu_calc_voltage_level(int cdclk)
+{
+	if (cdclk > 556800)
+		return 3;
+	else if (cdclk > 480000)
+		return 2;
+	else if (cdclk > 312000)
+		return 1;
+	else
+		return 0;
+}
+
 static void icl_readout_refclk(struct drm_i915_private *dev_priv,
 			       struct intel_cdclk_config *cdclk_config)
 {
@@ -3242,6 +3254,13 @@ static const struct intel_cdclk_funcs mtl_cdclk_funcs = {
 	.calc_voltage_level = tgl_calc_voltage_level,
 };
 
+static const struct intel_cdclk_funcs rplu_cdclk_funcs = {
+	.get_cdclk = bxt_get_cdclk,
+	.set_cdclk = bxt_set_cdclk,
+	.modeset_calc_cdclk = bxt_modeset_calc_cdclk,
+	.calc_voltage_level = rplu_calc_voltage_level,
+};
+
 static const struct intel_cdclk_funcs tgl_cdclk_funcs = {
 	.get_cdclk = bxt_get_cdclk,
 	.set_cdclk = bxt_set_cdclk,
@@ -3384,14 +3403,17 @@ void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv)
 		dev_priv->display.funcs.cdclk = &tgl_cdclk_funcs;
 		dev_priv->display.cdclk.table = dg2_cdclk_table;
 	} else if (IS_ALDERLAKE_P(dev_priv)) {
-		dev_priv->display.funcs.cdclk = &tgl_cdclk_funcs;
 		/* Wa_22011320316:adl-p[a0] */
-		if (IS_ADLP_DISPLAY_STEP(dev_priv, STEP_A0, STEP_B0))
+		if (IS_ADLP_DISPLAY_STEP(dev_priv, STEP_A0, STEP_B0)) {
 			dev_priv->display.cdclk.table = adlp_a_step_cdclk_table;
-		else if (IS_ADLP_RPLU(dev_priv))
+			dev_priv->display.funcs.cdclk = &tgl_cdclk_funcs;
+		} else if (IS_ADLP_RPLU(dev_priv)) {
 			dev_priv->display.cdclk.table = rplu_cdclk_table;
-		else
+			dev_priv->display.funcs.cdclk = &rplu_cdclk_funcs;
+		} else {
 			dev_priv->display.cdclk.table = adlp_cdclk_table;
+			dev_priv->display.funcs.cdclk = &tgl_cdclk_funcs;
+		}
 	} else if (IS_ROCKETLAKE(dev_priv)) {
 		dev_priv->display.funcs.cdclk = &tgl_cdclk_funcs;
 		dev_priv->display.cdclk.table = rkl_cdclk_table;