drm/i915/display: ignore long HPDs based on a flag

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.
Debugfs entry is added to control the ignore long hpd flag.

v2: Address patch styling comments (Jani Nikula)

v3: Ignoring the HPD moved to hotplug handler and now applies
    to all types of outputs (Imre Deak)

v4: use debugfs_create_bool and squash patches (Jani Nikula)

Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230215083832.287519-2-vinod.govindapillai@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
index fdab7bb93a7d6efb209a4ae5aae9d61db49ac7a9..b218e0507a88d951cada607392723ec5e98fdd1e 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display_core.h
+++ b/drivers/gpu/drm/i915/display/intel_display_core.h
@@ -183,6 +183,17 @@ 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_hotplug.c b/drivers/gpu/drm/i915/display/intel_hotplug.c
index 907ab7526cb47858b3357078ecb3f8c1122d10d3..b12900446828acf5871d044e6f56095394bb1f5e 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/display/intel_hotplug.c
@@ -389,6 +389,13 @@ static void i915_hotplug_work_func(struct work_struct *work)
 
        spin_unlock_irq(&dev_priv->irq_lock);
 
+       /* Skip calling encode hotplug handlers if ignore long HPD set*/
+       if (dev_priv->display.hotplug.ignore_long_hpd) {
+               drm_dbg_kms(&dev_priv->drm, "Ignore HPD flag on - skip encoder hotplug handlers\n");
+               mutex_unlock(&dev_priv->drm.mode_config.mutex);
+               return;
+       }
+
        drm_connector_list_iter_begin(&dev_priv->drm, &conn_iter);
        for_each_intel_connector_iter(connector, &conn_iter) {
                enum hpd_pin pin;
@@ -940,4 +947,6 @@ void intel_hpd_debugfs_register(struct drm_i915_private *i915)
                            i915, &i915_hpd_storm_ctl_fops);
        debugfs_create_file("i915_hpd_short_storm_ctl", 0644, minor->debugfs_root,
                            i915, &i915_hpd_short_storm_ctl_fops);
+       debugfs_create_bool("i915_ignore_long_hpd", 0644, minor->debugfs_root,
+                           &i915->display.hotplug.ignore_long_hpd);
 }