[Intel-gfx] [PATCH v2 1/2] drm/i915/display: ignore long HPDs based on a flag

[Vinod Govindapillai]

Some panels generate long HPD events even while connected to
the port. This cause some unexpected CI execution issues. A
new flag is added to track if such spurious long HPDs can be
ignored and are not processed further if the flag is set.

v2: Address patch styling comments (Jani Nikula)

Signed-off-by: Vinod Govindapillai <vinod.govindapillai at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display_core.h | 11 +++++++++++
 drivers/gpu/drm/i915/display/intel_dp.c           |  7 +++++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
index 96cf994b0ad1..f84a2e760ef4 100644
--- a/drivers/gpu/drm/i915/display/intel_display_core.h
+++ b/drivers/gpu/drm/i915/display/intel_display_core.h
@@ -170,6 +170,17 @@ struct intel_hotplug {
 	 * blocked behind the non-DP one.
 	 */
 	struct workqueue_struct *dp_wq;
+
+	/*
+	 * Flag to track if long HPDs need not to be processed
+	 *
+	 * Some panels generate long HPDs while keep connected to the port.
+	 * This can cause issues with CI tests results. In CI systems we
+	 * don't expect to disconnect the panels and could ignore the long
+	 * HPDs generated from the faulty panels. This flag can be used as
+	 * cue to ignore the long HPDs and can be set / unset using debugfs.
+	 */
+	bool ignore_long_hpd;
 };
 
 struct intel_vbt_data {
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 70b06806ec0d..87a0d01d8003 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5092,6 +5092,13 @@ intel_dp_hpd_pulse(struct intel_digital_port *dig_port, bool long_hpd)
 		return IRQ_HANDLED;
 	}
 
+	if (i915->display.hotplug.ignore_long_hpd && long_hpd) {
+		drm_dbg_kms(&i915->drm, "[ENCODER:%d:%s] ignoring long hpd\n",
+			    dig_port->base.base.base.id,
+			    dig_port->base.base.name);
+		return IRQ_HANDLED;
+	}
+
 	drm_dbg_kms(&i915->drm, "got hpd irq on [ENCODER:%d:%s] - %s\n",
 		    dig_port->base.base.base.id,
 		    dig_port->base.base.name,
-- 
2.34.1