From 7a22aca72a6228fa283a703c6b2cc6dc1ea866dc Mon Sep 17 00:00:00 2001
From: Sean Paul <seanpaul@chromium.org>
Date: Wed, 28 Aug 2019 20:09:44 -0400
Subject: drm/dp_mst: Clear all payload id tables downstream when initializing
Git-commit: f79489074c59a5fd6bc35b21ca9911237993a045
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322
It seems that on certain MST hubs, namely the CableMatters USB-C 2x DP
hub, using the DP_PAYLOAD_ALLOCATE_SET and DP_PAYLOAD_TABLE_UPDATE_STATUS
register ranges to clear any pre-existing payload allocations on the hub isn't
always enough to reset things if the source device has been reset unexpectedly.
Or at least, that's the current running theory. The precise behavior appears to
be that when the source device gets reset unexpectedly, the hub begins reporting
an available_pbn value of 0 for all of its ports. This is a bit inconsistent
with the our theory, since this seems to happen even if previously set PBN
allocations should have resulted in a non-zero available_pbn value. So, it's
possible that something else may be going on here.
Strangely though, sending a CLEAR_PAYLOAD_ID_TABLE broadcast request when
initializing the MST topology seems to bring things into working order and make
available_pbn work again. Since this is a pretty safe solution, let's go ahead
and implement it.
Changes since v1:
* Change indenting on drm_dp_send_clear_payload_id_table() prototype
* Remove some braces in drm_dp_send_clear_payload_id_table()
* Reorganize some variable declarations in drm_dp_send_clear_payload_id_table()
* Don't forget to handle DP_CLEAR_PAYLOAD_ID_TABLE in
drm_dp_sideband_parse_reply()
* Move drm_dp_send_clear_payload_id_table() call into
drm_dp_mst_link_probe_work(), since we can't send sideband messages
while under lock in drm_dp_mst_topology_mgr_set_mst()
* Change commit message
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190829000944.20722-1-lyude@redhat.com
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 56 +++++++++++++++++++++++++++
include/drm/drm_dp_mst_helper.h | 12 +++++-
2 files changed, 66 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 354bc8b3ffa1..5b89c1d1f482 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -76,6 +76,11 @@ static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
struct drm_dp_mst_branch *mstb);
+
+static void
+drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
+ struct drm_dp_mst_branch *mstb);
+
static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
struct drm_dp_mst_branch *mstb,
struct drm_dp_mst_port *port);
@@ -952,6 +957,8 @@ static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
case DP_POWER_DOWN_PHY:
case DP_POWER_UP_PHY:
return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
+ case DP_CLEAR_PAYLOAD_ID_TABLE:
+ return true; /* since there's nothing to parse */
default:
DRM_ERROR("Got unknown reply 0x%02x (%s)\n", msg->req_type,
drm_dp_mst_req_type_str(msg->req_type));
@@ -1050,6 +1057,15 @@ static int build_link_address(struct drm_dp_sideband_msg_tx *msg)
return 0;
}
+static int build_clear_payload_id_table(struct drm_dp_sideband_msg_tx *msg)
+{
+ struct drm_dp_sideband_msg_req_body req;
+
+ req.req_type = DP_CLEAR_PAYLOAD_ID_TABLE;
+ drm_dp_encode_sideband_req(&req, msg);
+ return 0;
+}
+
static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg, int port_num)
{
struct drm_dp_sideband_msg_req_body req;
@@ -2566,10 +2582,14 @@ static void drm_dp_mst_link_probe_work(struct work_struct *work)
struct drm_device *dev = mgr->dev;
struct drm_dp_mst_branch *mstb;
int ret;
+ bool clear_payload_id_table;
mutex_lock(&mgr->probe_lock);
mutex_lock(&mgr->lock);
+ clear_payload_id_table = !mgr->payload_id_table_cleared;
+ mgr->payload_id_table_cleared = true;
+
mstb = mgr->mst_primary;
if (mstb) {
ret = drm_dp_mst_topology_try_get_mstb(mstb);
@@ -2582,6 +2602,19 @@ static void drm_dp_mst_link_probe_work(struct work_struct *work)
return;
}
+ /*
+ * Certain branch devices seem to incorrectly report an available_pbn
+ * of 0 on downstream sinks, even after clearing the
+ * DP_PAYLOAD_ALLOCATE_* registers in
+ * drm_dp_mst_topology_mgr_set_mst(). Namely, the CableMatters USB-C
+ * 2x DP hub. Sending a CLEAR_PAYLOAD_ID_TABLE message seems to make
+ * things work again.
+ */
+ if (clear_payload_id_table) {
+ DRM_DEBUG_KMS("Clearing payload ID table\n");
+ drm_dp_send_clear_payload_id_table(mgr, mstb);
+ }
+
ret = drm_dp_check_and_send_link_address(mgr, mstb);
drm_dp_mst_topology_put_mstb(mstb);
@@ -2908,6 +2941,28 @@ static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
return ret < 0 ? ret : changed;
}
+void drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
+ struct drm_dp_mst_branch *mstb)
+{
+ struct drm_dp_sideband_msg_tx *txmsg;
+ int len, ret;
+
+ txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+ if (!txmsg)
+ return;
+
+ txmsg->dst = mstb;
+ len = build_clear_payload_id_table(txmsg);
+
+ drm_dp_queue_down_tx(mgr, txmsg);
+
+ ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
+ if (ret > 0 && txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
+ DRM_DEBUG_KMS("clear payload table id nak received\n");
+
+ kfree(txmsg);
+}
+
static int
drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
struct drm_dp_mst_branch *mstb,
@@ -3501,6 +3556,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
mgr->payload_mask = 0;
set_bit(0, &mgr->payload_mask);
mgr->vcpi_mask = 0;
+ mgr->payload_id_table_cleared = false;
}
out_unlock:
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index c1bda7030e2d..cd6531a37321 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -561,7 +561,8 @@ struct drm_dp_mst_topology_mgr {
struct drm_dp_sideband_msg_rx up_req_recv;
/**
- * @lock: protects mst state, primary, dpcd.
+ * @lock: protects @mst_state, @mst_primary, @dpcd, and
+ * @payload_id_table_cleared.
*/
struct mutex lock;
@@ -576,7 +577,14 @@ struct drm_dp_mst_topology_mgr {
* @mst_state: If this manager is enabled for an MST capable port. False
* if no MST sink/branch devices is connected.
*/
- bool mst_state;
+ bool mst_state : 1;
+
+ /**
+ * @payload_id_table_cleared: Whether or not we've cleared the payload
+ * ID table for @mst_primary. Protected by @lock.
+ */
+ bool payload_id_table_cleared : 1;
+
/**
* @mst_primary: Pointer to the primary/first branch device.
*/
--
2.28.0