[3.19.y-ckt stable] Patch "drm/dp/mst: fixup handling hotplug on port removal." has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    drm/dp/mst: fixup handling hotplug on port removal.

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt10.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From ae2be527ed6fc020a97016e611efddc9e2833907 Mon Sep 17 00:00:00 2001
From: Dave Airlie <airlied at redhat.com>
Date: Wed, 16 Sep 2015 10:37:28 +1000
Subject: drm/dp/mst: fixup handling hotplug on port removal.

commit df4839fdc9b3c922586b945f062f38cbbda022bb upstream.

output ports should always have a connector, unless
in the rare case connector allocation fails in the
driver.

In this case we only need to teardown the pdt,
and free the struct, and there is no need to
send a hotplug msg.

In the case were we add the port to the destroy
list we need to send a hotplug if we destroy
any connectors, so userspace knows to reprobe
stuff.

this patch also handles port->connector allocation
failing which should be a rare event, but makes
the code consistent.

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Signed-off-by: Dave Airlie <airlied at redhat.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 36 +++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 6c0a1b0..ce40117 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -859,29 +859,33 @@ static void drm_dp_destroy_port(struct kref *kref)
 {
 	struct drm_dp_mst_port *port = container_of(kref, struct drm_dp_mst_port, kref);
 	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
+
 	if (!port->input) {
 		port->vcpi.num_slots = 0;

 		kfree(port->cached_edid);

-		/* we can't destroy the connector here, as
-		   we might be holding the mode_config.mutex
-		   from an EDID retrieval */
+		/*
+		 * The only time we don't have a connector
+		 * on an output port is if the connector init
+		 * fails.
+		 */
 		if (port->connector) {
+			/* we can't destroy the connector here, as
+			 * we might be holding the mode_config.mutex
+			 * from an EDID retrieval */
+
 			mutex_lock(&mgr->destroy_connector_lock);
 			list_add(&port->next, &mgr->destroy_connector_list);
 			mutex_unlock(&mgr->destroy_connector_lock);
 			schedule_work(&mgr->destroy_connector_work);
 			return;
 		}
+		/* no need to clean up vcpi
+		 * as if we have no connector we never setup a vcpi */
 		drm_dp_port_teardown_pdt(port, port->pdt);
-
-		if (!port->input && port->vcpi.vcpi > 0)
-			drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
 	}
 	kfree(port);
-
-	(*mgr->cbs->hotplug)(mgr);
 }

 static void drm_dp_put_port(struct drm_dp_mst_port *port)
@@ -1111,12 +1115,21 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
 		char proppath[255];
 		build_mst_prop_path(port, mstb, proppath, sizeof(proppath));
 		port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, port, proppath);
-
+		if (!port->connector) {
+			/* remove it from the port list */
+			mutex_lock(&mstb->mgr->lock);
+			list_del(&port->next);
+			mutex_unlock(&mstb->mgr->lock);
+			/* drop port list reference */
+			drm_dp_put_port(port);
+			goto out;
+		}
 		if (port->port_num >= 8) {
 			port->cached_edid = drm_get_edid(port->connector, &port->aux.ddc);
 		}
 	}

+out:
 	/* put reference to this port */
 	drm_dp_put_port(port);
 }
@@ -2643,7 +2656,7 @@ static void drm_dp_destroy_connector_work(struct work_struct *work)
 {
 	struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, destroy_connector_work);
 	struct drm_dp_mst_port *port;
-
+	bool send_hotplug = false;
 	/*
 	 * Not a regular list traverse as we have to drop the destroy
 	 * connector lock before destroying the connector, to avoid AB->BA
@@ -2666,7 +2679,10 @@ static void drm_dp_destroy_connector_work(struct work_struct *work)
 		if (!port->input && port->vcpi.vcpi > 0)
 			drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
 		kfree(port);
+		send_hotplug = true;
 	}
+	if (send_hotplug)
+		(*mgr->cbs->hotplug)(mgr);
 }

 /**
--
1.9.1