[PATCH v2] drm/dp_mst: Clear MSG_RDY flag before sending new message
Wayne Lin
Wayne.Lin at amd.com
Thu Apr 27 07:28:49 UTC 2023
[Why]
The sequence for collecting down_reply from source perspective should
be:
Request_n->repeat (get partial reply of Request_n->clear message ready
flag to ack DPRX that the message is received) till all partial
replies for Request_n are received->new Request_n+1.
Now there is chance that drm_dp_mst_hpd_irq() will fire new down
request in the tx queue when the down reply is incomplete. Source is
restricted to generate interveleaved message transactions so we should
avoid it.
Also, while assembling partial reply packets, reading out DPCD DOWN_REP
Sideband MSG buffer + clearing DOWN_REP_MSG_RDY flag should be
wrapped up as a complete operation for reading out a reply packet.
Kicking off a new request before clearing DOWN_REP_MSG_RDY flag might
be risky. e.g. If the reply of the new request has overwritten the
DPRX DOWN_REP Sideband MSG buffer before source writing one to clear
DOWN_REP_MSG_RDY flag, source then unintentionally flushes the reply
for the new request. Should handle the up request in the same way.
[How]
Separete drm_dp_mst_hpd_irq() into 2 steps. After acking the MST IRQ
event, driver calls drm_dp_mst_hpd_irq_step2() and might trigger
drm_dp_mst_kick_tx() only when there is no on going message transaction.
Changes since v1:
* Reworked on review comments received
-> Adjust the fix to let driver explicitly kick off new down request
when mst irq event is handled and acked
-> Adjust the commit message
Signed-off-by: Wayne Lin <Wayne.Lin at amd.com>
Cc: stable at vger.kernel.org
---
.../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 8 ++---
drivers/gpu/drm/display/drm_dp_mst_topology.c | 35 ++++++++++++++++---
drivers/gpu/drm/i915/display/intel_dp.c | 5 ++-
drivers/gpu/drm/nouveau/dispnv50/disp.c | 5 ++-
include/drm/display/drm_dp_mst_helper.h | 4 +--
5 files changed, 45 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 1ad67c2a697e..48bdcb2ee9b1 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -3259,10 +3259,9 @@ static void dm_handle_mst_sideband_msg(struct amdgpu_dm_connector *aconnector)
DRM_DEBUG_DRIVER("ESI %02x %02x %02x\n", esi[0], esi[1], esi[2]);
/* handle HPD short pulse irq */
if (aconnector->mst_mgr.mst_state)
- drm_dp_mst_hpd_irq(
- &aconnector->mst_mgr,
- esi,
- &new_irq_handled);
+ drm_dp_mst_hpd_irq_step1(&aconnector->mst_mgr,
+ esi,
+ &new_irq_handled);
if (new_irq_handled) {
/* ACK at DPCD to notify down stream */
@@ -3281,6 +3280,7 @@ static void dm_handle_mst_sideband_msg(struct amdgpu_dm_connector *aconnector)
break;
}
+ drm_dp_mst_hpd_irq_step2(&aconnector->mst_mgr);
/* check if there is new irq to be handled */
dret = drm_dp_dpcd_read(
&aconnector->dm_dp_aux.aux,
diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 70df29fe92db..2e0a38a6509c 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -4045,7 +4045,7 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
}
/**
- * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
+ * drm_dp_mst_hpd_irq_step1() - MST hotplug IRQ notify
* @mgr: manager to notify irq for.
* @esi: 4 bytes from SINK_COUNT_ESI
* @handled: whether the hpd interrupt was consumed or not
@@ -4055,7 +4055,7 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
* topology manager will process the sideband messages received as a result
* of this.
*/
-int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
+int drm_dp_mst_hpd_irq_step1(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
{
int ret = 0;
int sc;
@@ -4077,11 +4077,38 @@ int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handl
*handled = true;
}
- drm_dp_mst_kick_tx(mgr);
return ret;
}
-EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
+EXPORT_SYMBOL(drm_dp_mst_hpd_irq_step1);
+
+/**
+ * drm_dp_mst_hpd_irq_step2() - MST hotplug IRQ 2nd part handling
+ * @mgr: manager to notify irq for.
+ *
+ * This should be called from the driver when mst irq event is handled
+ * and acked. Note that new down request should only be sent when
+ * previous message transaction is done. Source is not supposed to generate
+ * interleaved message transactions.
+ */
+void drm_dp_mst_hpd_irq_step2(struct drm_dp_mst_topology_mgr *mgr)
+{
+ struct drm_dp_sideband_msg_tx *txmsg;
+ bool skip = false;
+ mutex_lock(&mgr->qlock);
+ txmsg = list_first_entry_or_null(&mgr->tx_msg_downq,
+ struct drm_dp_sideband_msg_tx, next);
+ /* If last transaction is not completed yet*/
+ if (!txmsg ||
+ txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
+ txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
+ skip = true;
+ mutex_unlock(&mgr->qlock);
+
+ if (!skip)
+ drm_dp_mst_kick_tx(mgr);
+}
+EXPORT_SYMBOL(drm_dp_mst_hpd_irq_step2);
/**
* drm_dp_mst_detect_port() - get connection status for an MST port
* @connector: DRM connector for this port
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 75070eb07d4b..9a9a5aec9534 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3803,7 +3803,7 @@ intel_dp_mst_hpd_irq(struct intel_dp *intel_dp, u8 *esi, u8 *ack)
{
bool handled = false;
- drm_dp_mst_hpd_irq(&intel_dp->mst_mgr, esi, &handled);
+ drm_dp_mst_hpd_irq_step1(&intel_dp->mst_mgr, esi, &handled);
if (handled)
ack[1] |= esi[1] & (DP_DOWN_REP_MSG_RDY | DP_UP_REQ_MSG_RDY);
@@ -3880,6 +3880,9 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
if (!intel_dp_ack_sink_irq_esi(intel_dp, ack))
drm_dbg_kms(&i915->drm, "Failed to ack ESI\n");
+
+ if (ack[1] & (DP_DOWN_REP_MSG_RDY | DP_UP_REQ_MSG_RDY))
+ drm_dp_mst_hpd_irq_step2(&intel_dp->mst_mgr);
}
return link_ok;
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
index ed9d374147b8..00c36fcc8afd 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
@@ -1332,12 +1332,15 @@ nv50_mstm_service(struct nouveau_drm *drm,
break;
}
- drm_dp_mst_hpd_irq(&mstm->mgr, esi, &handled);
+ drm_dp_mst_hpd_irq_step1(&mstm->mgr, esi, &handled);
if (!handled)
break;
rc = drm_dp_dpcd_write(aux, DP_SINK_COUNT_ESI + 1, &esi[1],
3);
+
+ drm_dp_mst_hpd_irq_step2(&mstm->mgr);
+
if (rc != 3) {
ret = false;
break;
diff --git a/include/drm/display/drm_dp_mst_helper.h b/include/drm/display/drm_dp_mst_helper.h
index 32c764fb9cb5..6c08ba765d5a 100644
--- a/include/drm/display/drm_dp_mst_helper.h
+++ b/include/drm/display/drm_dp_mst_helper.h
@@ -815,8 +815,8 @@ void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr);
bool drm_dp_read_mst_cap(struct drm_dp_aux *aux, const u8 dpcd[DP_RECEIVER_CAP_SIZE]);
int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state);
-int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);
-
+int drm_dp_mst_hpd_irq_step1(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);
+void drm_dp_mst_hpd_irq_step2(struct drm_dp_mst_topology_mgr *mgr);
int
drm_dp_mst_detect_port(struct drm_connector *connector,
--
2.37.3
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