Patch "drm/dp/mst: process broadcast messages correctly" has been added to the 4.4-stable tree

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This is a note to let you know that I've just added the patch titled

    drm/dp/mst: process broadcast messages correctly

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-dp-mst-process-broadcast-messages-correctly.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From bd9343208704fcc70a5b919f228a7d26ae472727 Mon Sep 17 00:00:00 2001
From: Mykola Lysenko <Mykola.Lysenko@xxxxxxx>
Date: Fri, 18 Dec 2015 17:14:42 -0500
Subject: drm/dp/mst: process broadcast messages correctly

From: Mykola Lysenko <Mykola.Lysenko@xxxxxxx>

commit bd9343208704fcc70a5b919f228a7d26ae472727 upstream.

In case broadcast message received in UP request,
RAD cannot be used to identify message originator.
Message should be parsed, originator should be found
by GUID from parsed message.

Also reply with broadcast in case broadcast message
received (for now it is always broadcast)

Acked-by: Dave Airlie <airlied@xxxxxxxxx>
Signed-off-by: Mykola Lysenko <Mykola.Lysenko@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/gpu/drm/drm_dp_mst_topology.c |   95 ++++++++++++++++++++++++++++++----
 1 file changed, 84 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1210,6 +1210,50 @@ out:
 	return mstb;
 }
 
+static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper(
+	struct drm_dp_mst_branch *mstb,
+	uint8_t *guid)
+{
+	struct drm_dp_mst_branch *found_mstb;
+	struct drm_dp_mst_port *port;
+
+	list_for_each_entry(port, &mstb->ports, next) {
+		if (!port->mstb)
+			continue;
+
+		if (port->guid_valid && memcmp(port->guid, guid, 16) == 0)
+			return port->mstb;
+
+		found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid);
+
+		if (found_mstb)
+			return found_mstb;
+	}
+
+	return NULL;
+}
+
+static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device_by_guid(
+	struct drm_dp_mst_topology_mgr *mgr,
+	uint8_t *guid)
+{
+	struct drm_dp_mst_branch *mstb;
+
+	/* find the port by iterating down */
+	mutex_lock(&mgr->lock);
+
+	if (mgr->guid_valid && memcmp(mgr->guid, guid, 16) == 0)
+		mstb = mgr->mst_primary;
+	else
+		mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
+
+	if (mstb)
+		kref_get(&mstb->kref);
+
+	mutex_unlock(&mgr->lock);
+	return mstb;
+}
+
 static void drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
 					       struct drm_dp_mst_branch *mstb)
 {
@@ -1320,6 +1364,7 @@ static int set_hdr_from_dst_qlock(struct
 				  struct drm_dp_sideband_msg_tx *txmsg)
 {
 	struct drm_dp_mst_branch *mstb = txmsg->dst;
+	u8 req_type;
 
 	/* both msg slots are full */
 	if (txmsg->seqno == -1) {
@@ -1336,7 +1381,13 @@ static int set_hdr_from_dst_qlock(struct
 			txmsg->seqno = 1;
 		mstb->tx_slots[txmsg->seqno] = txmsg;
 	}
-	hdr->broadcast = 0;
+
+	req_type = txmsg->msg[0] & 0x7f;
+	if (req_type == DP_CONNECTION_STATUS_NOTIFY ||
+		req_type == DP_RESOURCE_STATUS_NOTIFY)
+		hdr->broadcast = 1;
+	else
+		hdr->broadcast = 0;
 	hdr->path_msg = txmsg->path_msg;
 	hdr->lct = mstb->lct;
 	hdr->lcr = mstb->lct - 1;
@@ -2145,28 +2196,50 @@ static int drm_dp_mst_handle_up_req(stru
 
 	if (mgr->up_req_recv.have_eomt) {
 		struct drm_dp_sideband_msg_req_body msg;
-		struct drm_dp_mst_branch *mstb;
+		struct drm_dp_mst_branch *mstb = NULL;
 		bool seqno;
-		mstb = drm_dp_get_mst_branch_device(mgr,
-						    mgr->up_req_recv.initial_hdr.lct,
-						    mgr->up_req_recv.initial_hdr.rad);
-		if (!mstb) {
-			DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
-			memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
-			return 0;
+
+		if (!mgr->up_req_recv.initial_hdr.broadcast) {
+			mstb = drm_dp_get_mst_branch_device(mgr,
+							    mgr->up_req_recv.initial_hdr.lct,
+							    mgr->up_req_recv.initial_hdr.rad);
+			if (!mstb) {
+				DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
+				memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+				return 0;
+			}
 		}
 
 		seqno = mgr->up_req_recv.initial_hdr.seqno;
 		drm_dp_sideband_parse_req(&mgr->up_req_recv, &msg);
 
 		if (msg.req_type == DP_CONNECTION_STATUS_NOTIFY) {
-			drm_dp_send_up_ack_reply(mgr, mstb, msg.req_type, seqno, false);
+			drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, msg.req_type, seqno, false);
+
+			if (!mstb)
+				mstb = drm_dp_get_mst_branch_device_by_guid(mgr, msg.u.conn_stat.guid);
+
+			if (!mstb) {
+				DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
+				memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+				return 0;
+			}
+
 			drm_dp_update_port(mstb, &msg.u.conn_stat);
 			DRM_DEBUG_KMS("Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n", msg.u.conn_stat.port_number, msg.u.conn_stat.legacy_device_plug_status, msg.u.conn_stat.displayport_device_plug_status, msg.u.conn_stat.message_capability_status, msg.u.conn_stat.input_port, msg.u.conn_stat.peer_device_type);
 			(*mgr->cbs->hotplug)(mgr);
 
 		} else if (msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
-			drm_dp_send_up_ack_reply(mgr, mstb, msg.req_type, seqno, false);
+			drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, msg.req_type, seqno, false);
+			if (!mstb)
+				mstb = drm_dp_get_mst_branch_device_by_guid(mgr, msg.u.resource_stat.guid);
+
+			if (!mstb) {
+				DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
+				memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+				return 0;
+			}
+
 			DRM_DEBUG_KMS("Got RSN: pn: %d avail_pbn %d\n", msg.u.resource_stat.port_number, msg.u.resource_stat.available_pbn);
 		}
 


Patches currently in stable-queue which might be from Mykola.Lysenko@xxxxxxx are

queue-4.4/drm-dp-mst-deallocate-payload-on-port-destruction.patch
queue-4.4/drm-dp-mst-process-broadcast-messages-correctly.patch
queue-4.4/drm-dp-mst-fix-in-rad-element-access.patch
queue-4.4/drm-dp-mst-always-send-reply-for-up-request.patch
queue-4.4/drm-dp-mst-fix-in-mstb-rad-initialization.patch
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