[PATCH 5.16 0874/1017] drm/i915: Reject unsupported TMDS rates on ICL+

Greg Kroah-Hartman
2022-04-05T10:17:27Z

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

commit 9cddf03b2af07443bebdc73cba21acb360c079e8 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/i915/display/intel_hdmi.c | 9 +++++++++
1 file changed, 9 insertions(+)

--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -1831,6 +1831,7 @@ hdmi_port_clock_valid(struct intel_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;
@@ -1851,6 +1852,14 @@ hdmi_port_clock_valid(struct intel_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.