linux-kernel - [PATCH 5.15 786/913] drm/i915: Reject unsupported TMDS rates on ICL+

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Message-Id: <20220405070403.394798356@linuxfoundation.org>
Date:   Tue,  5 Apr 2022 09:30:48 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        Mika Kahola <mika.kahola@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Subject: [PATCH 5.15 786/913] drm/i915: Reject unsupported TMDS rates on ICL+

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