From 8f0df907e81a94c11577a1de4cf2b682a2c33177 Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Mon, 18 Oct 2021 12:41:53 +0300
Subject: drm/i915/dp: Sanitize sink rate DPCD register values
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Git-commit: caae4fb537d8437b9290d8a1010adfaf174b29e6
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
If the DPCD sink rate values read from the sink are invalid, the
driver will sanitize this in intel_dp_set_common_rates(), by setting a
default 162000 link rate in common rates and printing a WARN().
WARN()s should only be triggered by bugs in the code and not by external
factors like the above (an invalid DPCD injected maliciously or read from a
buggy monitor). So fixup the invalid DPCD sink rate values already and print
an error in this case (since it's still a user visible problem).
Cc: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrj채l채 <ville.syrjala@linux.intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018094154.1407705-6-imre.deak@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/i915/display/intel_dp.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index bc4d73d54930..15028a0837f9 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -128,7 +128,7 @@ static void intel_dp_set_default_sink_rates(struct intel_dp *intel_dp)
}
/* update sink rates from dpcd */
-static void intel_dp_set_sink_rates(struct intel_dp *intel_dp)
+static void intel_dp_set_dpcd_sink_rates(struct intel_dp *intel_dp)
{
static const int dp_rates[] = {
162000, 270000, 540000, 810000
@@ -198,6 +198,25 @@ static void intel_dp_set_sink_rates(struct intel_dp *intel_dp)
intel_dp->num_sink_rates = i;
}
+static void intel_dp_set_sink_rates(struct intel_dp *intel_dp)
+{
+ struct intel_connector *connector = intel_dp->attached_connector;
+ struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+ struct intel_encoder *encoder = &intel_dig_port->base;
+
+ intel_dp_set_dpcd_sink_rates(intel_dp);
+
+ if (intel_dp->num_sink_rates)
+ return;
+
+ drm_err(&dp_to_i915(intel_dp)->drm,
+ "[CONNECTOR:%d:%s][ENCODER:%d:%s] Invalid DPCD with no link rates, using defaults\n",
+ connector->base.base.id, connector->base.name,
+ encoder->base.base.id, encoder->base.name);
+
+ intel_dp_set_default_sink_rates(intel_dp);
+}
+
static void intel_dp_set_default_max_sink_lane_count(struct intel_dp *intel_dp)
{
intel_dp->max_sink_lane_count = 1;
--
2.38.1