[Intel-gfx] [PATCH] drm/i915: Account for CD2X divider in ICL+ vco calculation

[Matt Roper]

When calculating the PLL ratio we were still assuming that the CD2X
divider is always /1.  For the new frequencies that use a /2 divider
that needs to be accounted for, otherwise our VCO result will be twice
as large as it should be.

Fixes: 3d1da92baffe ("drm/i915: Add 324mhz and 326.4mhz cdclks for gen11+")
Cc: José Roberto de Souza <jose.souza at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/display/intel_cdclk.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c
index 1329d3e60e26..55801aeefd1c 100644
--- a/drivers/gpu/drm/i915/display/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/display/intel_cdclk.c
@@ -1794,6 +1794,7 @@ static int icl_calc_cdclk(int min_cdclk, unsigned int ref)
 
 static int icl_calc_cdclk_pll_vco(struct drm_i915_private *dev_priv, int cdclk)
 {
+	int cd2xdiv;
 	int ratio;
 
 	if (cdclk == dev_priv->cdclk.hw.bypass)
@@ -1805,27 +1806,37 @@ static int icl_calc_cdclk_pll_vco(struct drm_i915_private *dev_priv, int cdclk)
 		/* fall through */
 	case 172800:
 	case 307200:
-	case 326400:
 	case 556800:
 	case 652800:
+		cd2xdiv = 1;
 		WARN_ON(dev_priv->cdclk.hw.ref != 19200 &&
 			dev_priv->cdclk.hw.ref != 38400);
 		break;
 	case 180000:
 	case 312000:
-	case 324000:
 	case 552000:
 	case 648000:
+		cd2xdiv = 1;
 		WARN_ON(dev_priv->cdclk.hw.ref != 24000);
 		break;
 	case 192000:
+		cd2xdiv = 1;
 		WARN_ON(dev_priv->cdclk.hw.ref != 19200 &&
 			dev_priv->cdclk.hw.ref != 38400 &&
 			dev_priv->cdclk.hw.ref != 24000);
 		break;
+	case 326400:
+		cd2xdiv = 2;
+		WARN_ON(dev_priv->cdclk.hw.ref != 19200 &&
+			dev_priv->cdclk.hw.ref != 38400);
+		break;
+	case 324000:
+		cd2xdiv = 2;
+		WARN_ON(dev_priv->cdclk.hw.ref != 24000);
+		break;
 	}
 
-	ratio = cdclk / (dev_priv->cdclk.hw.ref / 2);
+	ratio = cdclk / (dev_priv->cdclk.hw.ref / cd2xdiv / 2);
 
 	return dev_priv->cdclk.hw.ref * ratio;
 }
-- 
2.20.1