drm/i915: Reject unsupported TMDS rates on ICL+

ICL+ PLLs can't genenerate certain frequencies. Running the PLL
algorithms through for all frequencies 25-594MHz we see a gap just
above 500 MHz. Specifically 500-522.8MHZ for TC PLLs, and 500-533.2
MHz for combo PHY PLLs. Reject those frequencies hdmi_port_clock_valid()
so that we properly filter out unsupported modes and/or color depths
for HDMI.

Cc: stable@vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5247
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220311212845.32358-1-ville.syrjala@linux.intel.com
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
(cherry picked from commit e5086cb3f3d3f94091be29eec38cf13f8a75a778)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index 1aa5bdc..6512f01 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -1836,6 +1836,7 @@ hdmi_port_clock_valid(struct intel_hdmi *hdmi,
                      bool has_hdmi_sink)
 {
        struct drm_i915_private *dev_priv = intel_hdmi_to_i915(hdmi);
+       enum phy phy = intel_port_to_phy(dev_priv, hdmi_to_dig_port(hdmi)->base.port);
 
        if (clock < 25000)
                return MODE_CLOCK_LOW;
@@ -1856,6 +1857,14 @@ hdmi_port_clock_valid(struct intel_hdmi *hdmi,
        if (IS_CHERRYVIEW(dev_priv) && clock > 216000 && clock < 240000)
                return MODE_CLOCK_RANGE;
 
+       /* ICL+ combo PHY PLL can't generate 500-533.2 MHz */
+       if (intel_phy_is_combo(dev_priv, phy) && clock > 500000 && clock < 533200)
+               return MODE_CLOCK_RANGE;
+
+       /* ICL+ TC PHY PLL can't generate 500-532.8 MHz */
+       if (intel_phy_is_tc(dev_priv, phy) && clock > 500000 && clock < 532800)
+               return MODE_CLOCK_RANGE;
+
        /*
         * SNPS PHYs' MPLLB table-based programming can only handle a fixed
         * set of link rates.