[PATCH] drm/i915: add disable_edp module parameter to skip phantom eDP init

[mei . fan . liou]

From: "LIOU, Mei Fan" <mei.fan.liou@xxxxxxxxx>

Some platforms have BIOS/VBT that declares an eDP panel present while
no physical panel is connected. This causes intel_edp_init_connector()
to spend ~6 seconds waiting on PPS power sequencer and AUX channel
timeouts before failing gracefully.

Introduce a new boolean module parameter 'disable_edp' (default: false)
that allows users to skip eDP connector initialization entirely. When
set, the driver logs an informational message and returns false early
from intel_edp_init_connector(), bypassing all PPS/AUX probing.

This is modeled after the existing 'disable_display' parameter and
is intended as a workaround for headless or display-less deployments
where the BIOS incorrectly advertises an internal panel.

Signed-off-by: LIOU, Mei Fan <mei.fan.liou@xxxxxxxxx>
---
 drivers/gpu/drm/i915/display/intel_display_params.c | 3 +++
 drivers/gpu/drm/i915/display/intel_display_params.h | 1 +
 drivers/gpu/drm/i915/display/intel_dp.c             | 7 +++++++
 3 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_params.c b/drivers/gpu/drm/i915/display/intel_display_params.c
index 2aed110c5b09..8d47d19b1667 100644
--- a/drivers/gpu/drm/i915/display/intel_display_params.c
+++ b/drivers/gpu/drm/i915/display/intel_display_params.c
@@ -102,6 +102,9 @@ intel_display_param_named_unsafe(force_reset_modeset_test, bool, 0400,
 intel_display_param_named(disable_display, bool, 0400,
 	"Disable display (default: false)");
 
+intel_display_param_named(disable_edp, bool, 0400,
+	"Disable eDP panel init, skips PPS/AUX probing when VBT declares eDP but no panel is present (default: false)");
+
 intel_display_param_named(verbose_state_checks, bool, 0400,
 	"Enable verbose logs (ie. WARN_ON()) in case of unexpected hw state conditions.");
 
diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h b/drivers/gpu/drm/i915/display/intel_display_params.h
index b95ecf728daa..98ab0d753dab 100644
--- a/drivers/gpu/drm/i915/display/intel_display_params.h
+++ b/drivers/gpu/drm/i915/display/intel_display_params.h
@@ -41,6 +41,7 @@ struct drm_printer;
 	param(bool, load_detect_test, false, 0600) \
 	param(bool, force_reset_modeset_test, false, 0600) \
 	param(bool, disable_display, false, 0400) \
+	param(bool, disable_edp, false, 0400) \
 	param(bool, verbose_state_checks, true, 0400) \
 	param(bool, nuclear_pageflip, false, 0400) \
 	param(bool, enable_dp_mst, true, 0600) \
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 85d3aa3b9894..c6293a1b3840 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -7214,6 +7214,13 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
 	if (!intel_dp_is_edp(intel_dp))
 		return true;
 
+	if (display->params.disable_edp) {
+		drm_info(display->drm,
+			 "[ENCODER:%d:%s] eDP disabled by module parameter, skipping init\n",
+			 encoder->base.base.id, encoder->base.name);
+		return false;
+	}
+
 	/*
 	 * On IBX/CPT we may get here with LVDS already registered. Since the
 	 * driver uses the only internal power sequencer available for both
-- 
2.43.0