Commit caae4fb5 authored by Imre Deak's avatar Imre Deak
Browse files

drm/i915/dp: Sanitize sink rate DPCD register values 



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 Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: default avatarImre Deak <imre.deak@intel.com>
Reviewed-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018094154.1407705-6-imre.deak@intel.com
parent bedcadda

drivers/gpu/drm/i915/display/intel_dp.c

+20 −1
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ 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
@@ -197,6 +197,25 @@ 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;