Commit 40d2f582 authored by Suraj Kandpal's avatar Suraj Kandpal
Browse files

drm/i915/backlight: Remove try_vesa_interface 

Some panels need VESA DPCD AUX backlight but VBT says otherwise.
This is why we try with Intel backlight interface over VESA backlight
interface. This causes a blankout on such panels without any fallback
mechanism.
Remove try_vesa_interface and use VESA AUX backlight interface as a
fallback mechanism.
While at in sneak in a small comment cleanup too.

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15679


Signed-off-by: default avatarSuraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: default avatarAnkit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20260224031322.2568874-1-suraj.kandpal@intel.com
parent 4226479f

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

+7 −12
Original line number Diff line number Diff line
@@ -644,9 +644,10 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector) 
	struct intel_dp *intel_dp = intel_attached_dp(connector);

	struct drm_device *dev = connector->base.dev;

	struct intel_panel *panel = &connector->panel;

	bool try_intel_interface = false, try_vesa_interface = false;

	bool try_intel_interface = false;



	/* Check the VBT and user's module parameters to figure out which

	/*

	 * Check the VBT and user's module parameters to figure out which

	 * interfaces to probe

	 */

	switch (display->params.enable_dpcd_backlight) {
@@ -655,7 +656,6 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector) 
	case INTEL_DP_AUX_BACKLIGHT_AUTO:

		switch (panel->vbt.backlight.type) {

		case INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE:

			try_vesa_interface = true;

			break;

		case INTEL_BACKLIGHT_DISPLAY_DDI:

			try_intel_interface = true;
@@ -668,20 +668,12 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector) 
		if (panel->vbt.backlight.type != INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE)

			try_intel_interface = true;



		try_vesa_interface = true;

		break;

	case INTEL_DP_AUX_BACKLIGHT_FORCE_VESA:

		try_vesa_interface = true;

		break;

	case INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL:

		try_intel_interface = true;

		break;

	}



	/* For eDP 1.5 and above we are supposed to use VESA interface for brightness control */

	if (intel_dp->edp_dpcd[0] >= DP_EDP_15)

		try_vesa_interface = true;



	/*

	 * Since Intel has their own backlight control interface, the majority of machines out there

	 * using DPCD backlight controls with Intel GPUs will be using this interface as opposed to
@@ -694,6 +686,9 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector) 
	 * panel with Intel's OUI - which is also required for us to be able to detect Intel's

	 * backlight interface at all. This means that the only sensible way for us to detect both

	 * interfaces is to probe for Intel's first, and VESA's second.

	 *

	 * Also there is a chance some VBTs may advertise false Intel backlight support even if the

	 * TCON DPCD says otherwise. This means we keep VESA interface as fallback in that case.

	 */

	if (try_intel_interface && intel_dp_aux_supports_hdr_backlight(connector) &&

	    intel_dp->edp_dpcd[0] <= DP_EDP_14b) {
@@ -703,7 +698,7 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector) 
		return 0;

	}



	if (try_vesa_interface && intel_dp_aux_supports_vesa_backlight(connector)) {

	if (intel_dp_aux_supports_vesa_backlight(connector)) {

		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using VESA eDP backlight controls\n",

			    connector->base.base.id, connector->base.name);

		panel->backlight.funcs = &intel_dp_vesa_bl_funcs;