[PATCH v4 3/3] drm/i915: Send hotplug event if edid had changed.

[Stanislav Lisovskiy]

Added edid checking to dp and hdmi edid setting functions, which
are called from detect hooks. The result currently is propagated
to calling layer using drm_connector->change_counter(proposed by Daniel Vetter).
drm_helper_hpd_irq_event and intel_encoder_hotplug are currently both
responsible for checking if this counter or connection status is changed.

There are conflicting parts in drm and i915 which attempt
to do the same job - drm_helper_hpd_irq_event attempts to
check connector status changes and then call hotplug,
just as i915_hotplug_work_func, which calls encoder->hotplug
hook which in turn calls generic intel_encoder_hotplug function
which attempts to probe if output has changed.
Looks like both needs to be changed, so added edid checking
also to intel_encoder_hotplug function which is called both
for hdmi and dp.

v2: Renamed change counter to epoch counter. Fixed type name.

v3: Fixed rebase conflict

v4: Remove duplicate drm_edid_equal checks from hdmi and dp,
    lets use only once edid property is getting updated and
    increment epoch counter from there.
    Also lets now call drm_connector_update_edid_property
    right after we get edid always to make sure there is a
    unified way to handle edid change, without having to
    change tons of source code as currently
    drm_connector_update_edid_property is called only in
    certain cases like reprobing and not right after edid is
    actually updated.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105540
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 drivers/gpu/drm/drm_connector.c              | 16 +++++++++++++++
 drivers/gpu/drm/drm_edid.c                   |  3 +++
 drivers/gpu/drm/drm_probe_helper.c           |  2 +-
 drivers/gpu/drm/i915/display/intel_hotplug.c | 21 +++++++++++++++-----
 4 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 18b1ad2a4eee..828e57a740d7 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -1867,6 +1867,7 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
 	struct drm_device *dev = connector->dev;
 	size_t size = 0;
 	int ret;
+	const struct edid *old_edid;
 
 	/* ignore requests to set edid when overridden */
 	if (connector->override_edid)
@@ -1888,6 +1889,20 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
 	else
 		drm_reset_display_info(connector);
 
+	if (connector->edid_blob_ptr) {
+		old_edid = (struct edid *)connector->edid_blob_ptr->data;
+		if (old_edid) {
+			if (!drm_edid_are_equal(edid, old_edid)) {
+				DRM_DEBUG_KMS("[CONNECTOR:%d:%s] Edid was changed.\n",
+				    connector->base.id, connector->name);
+
+				connector->epoch_counter += 1;
+				DRM_DEBUG_KMS("Updating change counter to %llu\n",
+				    connector->epoch_counter);
+			}
+		}
+	}
+
 	drm_object_property_set_value(&connector->base,
 				      dev->mode_config.non_desktop_property,
 				      connector->display_info.non_desktop);
@@ -1898,6 +1913,7 @@ int drm_connector_update_edid_property(struct drm_connector *connector,
 	                                       edid,
 	                                       &connector->base,
 	                                       dev->mode_config.edid_property);
+
 	if (ret)
 		return ret;
 	return drm_connector_set_tile_property(connector);
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 6cd086ea6253..7a327aec00d7 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1803,6 +1803,9 @@ struct edid *drm_get_edid(struct drm_connector *connector,
 	edid = drm_do_get_edid(connector, drm_do_probe_ddc_edid, adapter);
 	if (edid)
 		drm_get_displayid(connector, edid);
+
+	drm_connector_update_edid_property(connector, edid);
+
 	return edid;
 }
 EXPORT_SYMBOL(drm_get_edid);
diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 5131ae56e676..d896d6b5d3b4 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -813,7 +813,7 @@ bool drm_helper_hpd_irq_event(struct drm_device *dev)
 			changed = true;
 		}
 
-		/* Check changing of edid when a connector status still remains
+		/* Check changing of epoch counter when a connector status still remains
 		 * as "connector_status_connected".
 		 */
 		if (connector->status == connector_status_connected &&
diff --git a/drivers/gpu/drm/i915/display/intel_hotplug.c b/drivers/gpu/drm/i915/display/intel_hotplug.c
index fc29046d48ea..5fc1d54b3e6a 100644
--- a/drivers/gpu/drm/i915/display/intel_hotplug.c
+++ b/drivers/gpu/drm/i915/display/intel_hotplug.c
@@ -280,23 +280,34 @@ intel_encoder_hotplug(struct intel_encoder *encoder,
 {
 	struct drm_device *dev = connector->base.dev;
 	enum drm_connector_status old_status;
+	u64 old_epoch_counter;
+	bool ret = false;
 
 	WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
 	old_status = connector->base.status;
 
+	old_epoch_counter = connector->base.epoch_counter;
+
 	connector->base.status =
 		drm_helper_probe_detect(&connector->base, NULL, false);
 
-	if (old_status == connector->base.status)
-		return INTEL_HOTPLUG_UNCHANGED;
+	if (old_status != connector->base.status)
+		ret = true;
+
+	if (old_epoch_counter != connector->base.epoch_counter)
+		ret = true;
 
-	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
+	if (ret) {
+		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s(change counter %llu)\n",
 		      connector->base.base.id,
 		      connector->base.name,
 		      drm_get_connector_status_name(old_status),
-		      drm_get_connector_status_name(connector->base.status));
+		      drm_get_connector_status_name(connector->base.status),
+		      connector->base.epoch_counter);
+		return INTEL_HOTPLUG_CHANGED;
+	}
 
-	return INTEL_HOTPLUG_CHANGED;
+	return INTEL_HOTPLUG_UNCHANGED;
 }
 
 static bool intel_encoder_has_hpd_pulse(struct intel_encoder *encoder)
-- 
2.17.1