[4.2.y-ckt stable] Patch "drm/dp/mst: always send reply for UP request" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

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

    drm/dp/mst: always send reply for UP request

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt3.

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

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 0cd90abff892364e12cf76fd9675ba3470099c06 Mon Sep 17 00:00:00 2001
From: Mykola Lysenko <Mykola.Lysenko at amd.com>
Date: Fri, 18 Dec 2015 17:14:43 -0500
Subject: drm/dp/mst: always send reply for UP request

commit 1f16ee7fa13649f4e55aa48ad31c3eb0722a62d3 upstream.

We should always send reply for UP request in order
to make downstream device clean-up resources appropriately.

Issue was that reply for UP request was sent only once.

Acked-by: Dave Airlie <airlied at gmail.com>
Signed-off-by: Mykola Lysenko <Mykola.Lysenko at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/gpu/drm/drm_dp_mst_topology.c | 30 +++++++++++-------------------
 include/drm/drm_dp_mst_helper.h       |  2 --
 2 files changed, 11 insertions(+), 21 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index d2b69db..d620fe9 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1489,26 +1489,18 @@ static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
 }

 /* called holding qlock */
-static void process_single_up_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
+static void process_single_up_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
+				       struct drm_dp_sideband_msg_tx *txmsg)
 {
-	struct drm_dp_sideband_msg_tx *txmsg;
 	int ret;

 	/* construct a chunk from the first msg in the tx_msg queue */
-	if (list_empty(&mgr->tx_msg_upq)) {
-		mgr->tx_up_in_progress = false;
-		return;
-	}
-
-	txmsg = list_first_entry(&mgr->tx_msg_upq, struct drm_dp_sideband_msg_tx, next);
 	ret = process_single_tx_qlock(mgr, txmsg, true);
-	if (ret == 1) {
-		/* up txmsgs aren't put in slots - so free after we send it */
-		list_del(&txmsg->next);
-		kfree(txmsg);
-	} else if (ret)
+
+	if (ret != 1)
 		DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
-	mgr->tx_up_in_progress = true;
+
+	txmsg->dst->tx_slots[txmsg->seqno] = NULL;
 }

 static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,
@@ -1893,11 +1885,12 @@ static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
 	drm_dp_encode_up_ack_reply(txmsg, req_type);

 	mutex_lock(&mgr->qlock);
-	list_add_tail(&txmsg->next, &mgr->tx_msg_upq);
-	if (!mgr->tx_up_in_progress) {
-		process_single_up_tx_qlock(mgr);
-	}
+
+	process_single_up_tx_qlock(mgr, txmsg);
+
 	mutex_unlock(&mgr->qlock);
+
+	kfree(txmsg);
 	return 0;
 }

@@ -2797,7 +2790,6 @@ int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
 	mutex_init(&mgr->qlock);
 	mutex_init(&mgr->payload_lock);
 	mutex_init(&mgr->destroy_connector_lock);
-	INIT_LIST_HEAD(&mgr->tx_msg_upq);
 	INIT_LIST_HEAD(&mgr->tx_msg_downq);
 	INIT_LIST_HEAD(&mgr->destroy_connector_list);
 	INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index a89f505..c7f01d1 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -449,9 +449,7 @@ struct drm_dp_mst_topology_mgr {
 	   the mstb tx_slots and txmsg->state once they are queued */
 	struct mutex qlock;
 	struct list_head tx_msg_downq;
-	struct list_head tx_msg_upq;
 	bool tx_down_in_progress;
-	bool tx_up_in_progress;

 	/* payload info + lock for it */
 	struct mutex payload_lock;
--
1.9.1