[PATCH 2/3] drm/mst: Support simultaneous down replies
Sean Paul
sean at poorly.run
Thu Feb 13 21:15:19 UTC 2020
From: Sean Paul <seanpaul at chromium.org>
Currently we have one down reply message servicing the mst manager, so
we need to serialize all tx msgs to ensure we only have one message in
flight at a time. For obvious reasons this is suboptimal (but less
suboptimal than the free-for-all we had before serialization).
This patch removes the single down_rep_recv message from manager and
adds 2 replies in the branch structure. The 2 replies mirrors the tx_slots
which we use to rate-limit outgoing messages and correspond to seqno in
the packet headers.
Cc: Wayne Lin <Wayne.Lin at amd.com>
Signed-off-by: Sean Paul <seanpaul at chromium.org>
---
drivers/gpu/drm/drm_dp_mst_topology.c | 80 ++++++++++++++++-----------
include/drm/drm_dp_mst_helper.h | 59 ++++++++++----------
2 files changed, 78 insertions(+), 61 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index e8bb39bb17a0f..7e6a82efdfc02 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -3690,7 +3690,8 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
}
EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
-static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
+static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up,
+ struct drm_dp_mst_branch **mstb, int *seqno)
{
int len;
u8 replyblock[32];
@@ -3702,7 +3703,8 @@ static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE :
DP_SIDEBAND_MSG_DOWN_REP_BASE;
- msg = up ? &mgr->up_req_recv : &mgr->down_rep_recv;
+ *mstb = NULL;
+ *seqno = -1;
len = min(mgr->max_dpcd_transaction_bytes, 16);
ret = drm_dp_dpcd_read(mgr->aux, basereg, replyblock, len);
@@ -3719,6 +3721,21 @@ static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
return false;
}
+ *seqno = hdr.seqno;
+
+ if (up) {
+ msg = &mgr->up_req_recv;
+ } else {
+ /* Caller is responsible for giving back this reference */
+ *mstb = drm_dp_get_mst_branch_device(mgr, hdr.lct, hdr.rad);
+ if (!*mstb) {
+ DRM_DEBUG_KMS("Got MST reply from unknown device %d\n",
+ hdr.lct);
+ return false;
+ }
+ msg = &(*mstb)->down_rep_recv[hdr.seqno];
+ }
+
if (!drm_dp_sideband_msg_set_header(msg, &hdr, hdrlen)) {
DRM_DEBUG_KMS("sideband msg set header failed %d\n",
replyblock[0]);
@@ -3759,53 +3776,52 @@ static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
{
struct drm_dp_sideband_msg_tx *txmsg;
- struct drm_dp_mst_branch *mstb;
- struct drm_dp_sideband_msg_hdr *hdr = &mgr->down_rep_recv.initial_hdr;
- int slot = -1;
+ struct drm_dp_mst_branch *mstb = NULL;
+ struct drm_dp_sideband_msg_rx *msg = NULL;
+ int seqno = -1;
- if (!drm_dp_get_one_sb_msg(mgr, false))
- goto clear_down_rep_recv;
+ if (!drm_dp_get_one_sb_msg(mgr, false, &mstb, &seqno))
+ goto out_clear_reply;
- if (!mgr->down_rep_recv.have_eomt)
- return 0;
+ msg = &mstb->down_rep_recv[seqno];
- mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad);
- if (!mstb) {
- DRM_DEBUG_KMS("Got MST reply from unknown device %d\n",
- hdr->lct);
- goto clear_down_rep_recv;
- }
+ /* Multi-packet message transmission, don't clear the reply */
+ if (!msg->have_eomt)
+ goto out;
/* find the message */
- slot = hdr->seqno;
mutex_lock(&mgr->qlock);
- txmsg = mstb->tx_slots[slot];
+ txmsg = mstb->tx_slots[seqno];
/* remove from slots */
mutex_unlock(&mgr->qlock);
if (!txmsg) {
+ struct drm_dp_sideband_msg_hdr *hdr;
+ hdr = &msg->initial_hdr;
DRM_DEBUG_KMS("Got MST reply with no msg %p %d %d %02x %02x\n",
mstb, hdr->seqno, hdr->lct, hdr->rad[0],
- mgr->down_rep_recv.msg[0]);
- goto no_msg;
+ msg->msg[0]);
+ goto out_clear_reply;
}
- drm_dp_sideband_parse_reply(&mgr->down_rep_recv, &txmsg->reply);
+ drm_dp_sideband_parse_reply(msg, &txmsg->reply);
- if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
+ if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
DRM_DEBUG_KMS("Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
txmsg->reply.req_type,
drm_dp_mst_req_type_str(txmsg->reply.req_type),
txmsg->reply.u.nak.reason,
drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
txmsg->reply.u.nak.nak_data);
+ goto out_clear_reply;
+ }
- memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+ memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
drm_dp_mst_topology_put_mstb(mstb);
mutex_lock(&mgr->qlock);
txmsg->state = DRM_DP_SIDEBAND_TX_RX;
- mstb->tx_slots[slot] = NULL;
+ mstb->tx_slots[seqno] = NULL;
mgr->is_waiting_for_dwn_reply = false;
mutex_unlock(&mgr->qlock);
@@ -3813,13 +3829,15 @@ static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
return 0;
-no_msg:
- drm_dp_mst_topology_put_mstb(mstb);
-clear_down_rep_recv:
+out_clear_reply:
mutex_lock(&mgr->qlock);
mgr->is_waiting_for_dwn_reply = false;
mutex_unlock(&mgr->qlock);
- memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+ if (msg)
+ memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
+out:
+ if (mstb)
+ drm_dp_mst_topology_put_mstb(mstb);
return 0;
}
@@ -3895,11 +3913,10 @@ static void drm_dp_mst_up_req_work(struct work_struct *work)
static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
{
- struct drm_dp_sideband_msg_hdr *hdr = &mgr->up_req_recv.initial_hdr;
struct drm_dp_pending_up_req *up_req;
- bool seqno;
+ int seqno;
- if (!drm_dp_get_one_sb_msg(mgr, true))
+ if (!drm_dp_get_one_sb_msg(mgr, true, NULL, &seqno))
goto out;
if (!mgr->up_req_recv.have_eomt)
@@ -3912,7 +3929,6 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
}
INIT_LIST_HEAD(&up_req->next);
- seqno = hdr->seqno;
drm_dp_sideband_parse_req(&mgr->up_req_recv, &up_req->msg);
if (up_req->msg.req_type != DP_CONNECTION_STATUS_NOTIFY &&
@@ -3946,7 +3962,7 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
res_stat->available_pbn);
}
- up_req->hdr = *hdr;
+ up_req->hdr = mgr->up_req_recv.initial_hdr;
mutex_lock(&mgr->up_req_lock);
list_add_tail(&up_req->next, &mgr->up_req_list);
mutex_unlock(&mgr->up_req_lock);
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 5483f888712ad..7d0341f94ce1b 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -160,6 +160,31 @@ struct drm_dp_mst_port {
bool fec_capable;
};
+/* sideband msg header - not bit struct */
+struct drm_dp_sideband_msg_hdr {
+ u8 lct;
+ u8 lcr;
+ u8 rad[8];
+ bool broadcast;
+ bool path_msg;
+ u8 msg_len;
+ bool somt;
+ bool eomt;
+ bool seqno;
+};
+
+struct drm_dp_sideband_msg_rx {
+ u8 chunk[48];
+ u8 msg[256];
+ u8 curchunk_len;
+ u8 curchunk_idx; /* chunk we are parsing now */
+ u8 curchunk_hdrlen;
+ u8 curlen; /* total length of the msg */
+ bool have_somt;
+ bool have_eomt;
+ struct drm_dp_sideband_msg_hdr initial_hdr;
+};
+
/**
* struct drm_dp_mst_branch - MST branch device.
* @rad: Relative Address to talk to this branch device.
@@ -232,24 +257,16 @@ struct drm_dp_mst_branch {
int last_seqno;
bool link_address_sent;
+ /**
+ * @down_rep_recv: Message receiver state for down replies.
+ */
+ struct drm_dp_sideband_msg_rx down_rep_recv[2];
+
/* global unique identifier to identify branch devices */
u8 guid[16];
};
-/* sideband msg header - not bit struct */
-struct drm_dp_sideband_msg_hdr {
- u8 lct;
- u8 lcr;
- u8 rad[8];
- bool broadcast;
- bool path_msg;
- u8 msg_len;
- bool somt;
- bool eomt;
- bool seqno;
-};
-
struct drm_dp_nak_reply {
u8 guid[16];
u8 reason;
@@ -306,18 +323,6 @@ struct drm_dp_remote_i2c_write_ack_reply {
};
-struct drm_dp_sideband_msg_rx {
- u8 chunk[48];
- u8 msg[256];
- u8 curchunk_len;
- u8 curchunk_idx; /* chunk we are parsing now */
- u8 curchunk_hdrlen;
- u8 curlen; /* total length of the msg */
- bool have_somt;
- bool have_eomt;
- struct drm_dp_sideband_msg_hdr initial_hdr;
-};
-
#define DRM_DP_MAX_SDP_STREAMS 16
struct drm_dp_allocate_payload {
u8 port_number;
@@ -556,10 +561,6 @@ struct drm_dp_mst_topology_mgr {
*/
int conn_base_id;
- /**
- * @down_rep_recv: Message receiver state for down replies.
- */
- struct drm_dp_sideband_msg_rx down_rep_recv;
/**
* @up_req_recv: Message receiver state for up requests.
*/
--
Sean Paul, Software Engineer, Google / Chromium OS
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