[Intel-gfx] [PATCH] drm/i915: Fix ICL HDMI clock readout

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Copy the 38.4 vs. 19.2 MHz ref clock exception from the dpll
mgr into the clock readout function as well.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107722
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_ddi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index f3b115ce4029..68b301e6f41d 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1416,6 +1416,13 @@ static int cnl_calc_wrpll_link(struct drm_i915_private *dev_priv,
 
 	ref_clock = dev_priv->cdclk.hw.ref;
 
+	/*
+	 * For ICL, the spec states: if reference frequency is 38.4, use 19.2
+	 * because the DPLL automatically divides that by 2.
+	 */
+	if (IS_ICELAKE(dev_priv) && ref_clock == 38400)
+		ref_clock = 19200;
+
 	dco_freq = (cfgcr0 & DPLL_CFGCR0_DCO_INTEGER_MASK) * ref_clock;
 
 	dco_freq += (((cfgcr0 & DPLL_CFGCR0_DCO_FRACTION_MASK) >>
-- 
2.16.4