Merge tag 'drm-intel-fixes-2023-09-14' of...

Merge tag 'drm-intel-fixes-2023-09-14' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes

- Only check eDP HPD when AUX CH is shared.
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ZQL+NqtIZH5F/Nxr@intel.com

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

@@ -3540,6 +3540,27 @@ enum aux_ch intel_bios_dp_aux_ch(const struct intel_bios_encoder_data *devdata)
 	return map_aux_ch(devdata->i915, devdata->child.aux_channel);
 }
 
+bool intel_bios_dp_has_shared_aux_ch(const struct intel_bios_encoder_data *devdata)
+{
+	struct drm_i915_private *i915;
+	u8 aux_channel;
+	int count = 0;
+
+	if (!devdata || !devdata->child.aux_channel)
+		return false;
+
+	i915 = devdata->i915;
+	aux_channel = devdata->child.aux_channel;
+
+	list_for_each_entry(devdata, &i915->display.vbt.display_devices, node) {
+		if (intel_bios_encoder_supports_dp(devdata) &&
+		    aux_channel == devdata->child.aux_channel)
+			count++;
+	}
+
+	return count > 1;
+}
+
 int intel_bios_dp_boost_level(const struct intel_bios_encoder_data *devdata)
 {
 	if (!devdata || devdata->i915->display.vbt.version < 196 || !devdata->child.iboost)

drivers/gpu/drm/i915/display/intel_bios.h

@@ -273,6 +273,7 @@ enum aux_ch intel_bios_dp_aux_ch(const struct intel_bios_encoder_data *devdata);
 int intel_bios_dp_boost_level(const struct intel_bios_encoder_data *devdata);
 int intel_bios_dp_max_lane_count(const struct intel_bios_encoder_data *devdata);
 int intel_bios_dp_max_link_rate(const struct intel_bios_encoder_data *devdata);
+bool intel_bios_dp_has_shared_aux_ch(const struct intel_bios_encoder_data *devdata);
 int intel_bios_hdmi_boost_level(const struct intel_bios_encoder_data *devdata);
 int intel_bios_hdmi_ddc_pin(const struct intel_bios_encoder_data *devdata);
 int intel_bios_hdmi_level_shift(const struct intel_bios_encoder_data *devdata);

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

@@ -5512,8 +5512,13 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 	/*
 	 * VBT and straps are liars. Also check HPD as that seems
 	 * to be the most reliable piece of information available.
+	 *
+	 * ... expect on devices that forgot to hook HPD up for eDP
+	 * (eg. Acer Chromebook C710), so we'll check it only if multiple
+	 * ports are attempting to use the same AUX CH, according to VBT.
 	 */
-	if (!intel_digital_port_connected(encoder)) {
+	if (intel_bios_dp_has_shared_aux_ch(encoder->devdata) &&
+	    !intel_digital_port_connected(encoder)) {
 		/*
 		 * If this fails, presume the DPCD answer came
 		 * from some other port using the same AUX CH.