[PATCH v2 1/4] dp/dp_mst: Add support for sink event notify messages

[PATCH v2 1/4] dp/dp_mst: Add support for sink event notify messages

[Sam McNally]

Sink event notify messages are used for MST CEC IRQs. Add parsing
support for sink event notify messages in preparation for handling MST
CEC IRQs.

Signed-off-by: Sam McNally <sammc@chromium.org>
---

(no changes since v1)

 drivers/gpu/drm/drm_dp_mst_topology.c | 37 ++++++++++++++++++++++++++-
 include/drm/drm_dp_mst_helper.h       | 14 ++++++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 17dbed0a9800..15b6cc39a754 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1027,6 +1027,30 @@ static bool drm_dp_sideband_parse_resource_status_notify(struct drm_dp_sideband_
 	return false;
 }
 
+static bool drm_dp_sideband_parse_sink_event_notify(
+	struct drm_dp_sideband_msg_rx *raw,
+	struct drm_dp_sideband_msg_req_body *msg)
+{
+	int idx = 1;
+
+	msg->u.sink_event.port_number = (raw->msg[idx] & 0xf0) >> 4;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+
+	memcpy(msg->u.sink_event.guid, &raw->msg[idx], 16);
+	idx += 16;
+	if (idx > raw->curlen)
+		goto fail_len;
+
+	msg->u.sink_event.event_id = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
+	idx++;
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("sink event notify parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
 static bool drm_dp_sideband_parse_req(struct drm_dp_sideband_msg_rx *raw,
 				      struct drm_dp_sideband_msg_req_body *msg)
 {
@@ -1038,6 +1062,8 @@ static bool drm_dp_sideband_parse_req(struct drm_dp_sideband_msg_rx *raw,
 		return drm_dp_sideband_parse_connection_status_notify(raw, msg);
 	case DP_RESOURCE_STATUS_NOTIFY:
 		return drm_dp_sideband_parse_resource_status_notify(raw, msg);
+	case DP_SINK_EVENT_NOTIFY:
+		return drm_dp_sideband_parse_sink_event_notify(raw, msg);
 	default:
 		DRM_ERROR("Got unknown request 0x%02x (%s)\n", msg->req_type,
 			  drm_dp_mst_req_type_str(msg->req_type));
@@ -3875,6 +3901,8 @@ drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr,
 			guid = msg->u.conn_stat.guid;
 		else if (msg->req_type == DP_RESOURCE_STATUS_NOTIFY)
 			guid = msg->u.resource_stat.guid;
+		else if (msg->req_type == DP_SINK_EVENT_NOTIFY)
+			guid = msg->u.sink_event.guid;
 
 		if (guid)
 			mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid);
@@ -3948,7 +3976,8 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
 	drm_dp_sideband_parse_req(&mgr->up_req_recv, &up_req->msg);
 
 	if (up_req->msg.req_type != DP_CONNECTION_STATUS_NOTIFY &&
-	    up_req->msg.req_type != DP_RESOURCE_STATUS_NOTIFY) {
+	    up_req->msg.req_type != DP_RESOURCE_STATUS_NOTIFY &&
+	    up_req->msg.req_type != DP_SINK_EVENT_NOTIFY) {
 		DRM_DEBUG_KMS("Received unknown up req type, ignoring: %x\n",
 			      up_req->msg.req_type);
 		kfree(up_req);
@@ -3976,6 +4005,12 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
 		DRM_DEBUG_KMS("Got RSN: pn: %d avail_pbn %d\n",
 			      res_stat->port_number,
 			      res_stat->available_pbn);
+	} else if (up_req->msg.req_type == DP_SINK_EVENT_NOTIFY) {
+		const struct drm_dp_sink_event_notify *sink_event =
+			&up_req->msg.u.sink_event;
+
+		DRM_DEBUG_KMS("Got SEN: pn: %d event_id %d\n",
+			      sink_event->port_number, sink_event->event_id);
 	}
 
 	up_req->hdr = mgr->up_req_recv.initial_hdr;
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 6ae5860d8644..c7c79e0ced18 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -402,6 +402,19 @@ struct drm_dp_resource_status_notify {
 	u16 available_pbn;
 };
 
+#define DP_SINK_EVENT_PANEL_REPLAY_ACTIVE_FRAME_CRC_ERROR	BIT(0)
+#define DP_SINK_EVENT_PANEL_REPLAY_RFB_STORAGE_ERROR		BIT(1)
+#define DP_SINK_EVENT_DSC_RC_BUFFER_UNDER_RUN			BIT(2)
+#define DP_SINK_EVENT_DSC_RC_BUFFER_OVERFLOW			BIT(3)
+#define DP_SINK_EVENT_DSC_CHUNK_LENGTH_ERROR			BIT(4)
+#define DP_SINK_EVENT_CEC_IRQ_EVENT				BIT(5)
+
+struct drm_dp_sink_event_notify {
+	u8 port_number;
+	u8 guid[16];
+	u16 event_id;
+};
+
 struct drm_dp_query_payload_ack_reply {
 	u8 port_number;
 	u16 allocated_pbn;
@@ -413,6 +426,7 @@ struct drm_dp_sideband_msg_req_body {
 		struct drm_dp_connection_status_notify conn_stat;
 		struct drm_dp_port_number_req port_num;
 		struct drm_dp_resource_status_notify resource_stat;
+		struct drm_dp_sink_event_notify sink_event;
 
 		struct drm_dp_query_payload query_payload;
 		struct drm_dp_allocate_payload allocate_payload;
-- 
2.28.0.526.ge36021eeef-goog

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[PATCH v2 2/4] drm_dp_mst_topology: use correct AUX channel

[Sam McNally]

From: Hans Verkuil <hans.verkuil@cisco.com>

For adapters behind an MST hub use the correct AUX channel.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
[sammc@chromium.org: rebased, removing redundant changes]
Signed-off-by: Sam McNally <sammc@chromium.org>
---

(no changes since v1)

 drivers/gpu/drm/drm_dp_mst_topology.c | 36 +++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 15b6cc39a754..0d753201adbd 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2255,6 +2255,9 @@ drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
 	drm_dp_mst_topology_put_port(port);
 }
 
+static ssize_t
+drm_dp_mst_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg);
+
 static struct drm_dp_mst_port *
 drm_dp_mst_add_port(struct drm_device *dev,
 		    struct drm_dp_mst_topology_mgr *mgr,
@@ -2271,9 +2274,13 @@ drm_dp_mst_add_port(struct drm_device *dev,
 	port->port_num = port_number;
 	port->mgr = mgr;
 	port->aux.name = "DPMST";
+	mutex_init(&port->aux.hw_mutex);
+	mutex_init(&port->aux.cec.lock);
 	port->aux.dev = dev->dev;
 	port->aux.is_remote = true;
 
+	port->aux.transfer = drm_dp_mst_aux_transfer;
+
 	/* initialize the MST downstream port's AUX crc work queue */
 	drm_dp_remote_aux_init(&port->aux);
 
@@ -3503,6 +3510,35 @@ static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
 	return 0;
 }
 
+static ssize_t
+drm_dp_mst_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
+{
+	struct drm_dp_mst_port *port =
+		container_of(aux, struct drm_dp_mst_port, aux);
+	int ret;
+
+	switch (msg->request & ~DP_AUX_I2C_MOT) {
+	case DP_AUX_NATIVE_WRITE:
+	case DP_AUX_I2C_WRITE:
+	case DP_AUX_I2C_WRITE_STATUS_UPDATE:
+		ret = drm_dp_send_dpcd_write(port->mgr, port, msg->address,
+					     msg->size, msg->buffer);
+		break;
+
+	case DP_AUX_NATIVE_READ:
+	case DP_AUX_I2C_READ:
+		ret = drm_dp_send_dpcd_read(port->mgr, port, msg->address,
+					    msg->size, msg->buffer);
+		break;
+
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
 static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8  dp_link_count)
 {
 	if (dp_link_bw == 0 || dp_link_count == 0)
-- 
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[PATCH v2 3/4] drm_dp_mst_topology: export two functions

[Sam McNally]

From: Hans Verkuil <hans.verkuil@cisco.com>

These are required for the CEC MST support.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Sam McNally <sammc@chromium.org>
---

(no changes since v1)

 drivers/gpu/drm/drm_dp_mst_topology.c | 6 ++----
 include/drm/drm_dp_mst_helper.h       | 4 ++++
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 0d753201adbd..c783a2a1c114 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -62,8 +62,6 @@ struct drm_dp_pending_up_req {
 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
 				  char *buf);
 
-static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
-
 static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
 				     int id,
 				     struct drm_dp_payload *payload);
@@ -1864,7 +1862,7 @@ static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port)
  * drm_dp_mst_topology_try_get_port()
  * drm_dp_mst_topology_get_port()
  */
-static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
+void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
 {
 	topology_ref_history_lock(port->mgr);
 
@@ -1935,7 +1933,7 @@ drm_dp_mst_topology_get_port_validated_locked(struct drm_dp_mst_branch *mstb,
 	return NULL;
 }
 
-static struct drm_dp_mst_port *
+struct drm_dp_mst_port *
 drm_dp_mst_topology_get_port_validated(struct drm_dp_mst_topology_mgr *mgr,
 				       struct drm_dp_mst_port *port)
 {
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index c7c79e0ced18..d036222e0d64 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -754,6 +754,10 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
 		       struct drm_dp_mst_topology_mgr *mgr,
 		       struct drm_dp_mst_port *port);
 
+struct drm_dp_mst_port *drm_dp_mst_topology_get_port_validated
+(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
+void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
+
 struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
 
 
-- 
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[PATCH v2 4/4] drm_dp_cec: add MST support

[Sam McNally]

With DP v2.0 errata E5, CEC tunneling can be supported through an MST
topology.

There are some minor differences for CEC tunneling through an MST
topology compared to CEC tunneling to an SST port:
- CEC IRQs are delivered via a sink event notify message
- CEC-related DPCD registers are accessed via remote DPCD reads and
  writes.

This results in the MST implementation diverging from the existing SST
implementation:
- sink event notify messages with CEC_IRQ ID set indicate CEC IRQ rather
  than ESI1
- setting edid and handling CEC IRQs, which can be triggered from
  contexts where locks held preclude HPD handling, are deferred to avoid
  remote DPCD access which would block until HPD handling is performed
  or a timeout

Register and unregister for all MST connectors, ensuring their
drm_dp_aux_cec struct won't be accessed uninitialized.

Signed-off-by: Sam McNally <sammc@chromium.org>
---

Changes in v2:
- Used aux->is_remote instead of aux->cec.is_mst, removing the need for
  the previous patch in the series
- Added a defensive check for null edid in the deferred set_edid work,
  in case the edid is no longer valid at that point

 drivers/gpu/drm/drm_dp_cec.c          | 69 +++++++++++++++++++++++++--
 drivers/gpu/drm/drm_dp_mst_topology.c | 24 ++++++++++
 include/drm/drm_dp_helper.h           |  4 ++
 3 files changed, 92 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c
index 3ab2609f9ec7..d708fc1e273a 100644
--- a/drivers/gpu/drm/drm_dp_cec.c
+++ b/drivers/gpu/drm/drm_dp_cec.c
@@ -14,6 +14,7 @@
 #include <drm/drm_connector.h>
 #include <drm/drm_device.h>
 #include <drm/drm_dp_helper.h>
+#include <drm/drm_dp_mst_helper.h>
 
 /*
  * Unfortunately it turns out that we have a chicken-and-egg situation
@@ -248,6 +249,10 @@ void drm_dp_cec_irq(struct drm_dp_aux *aux)
 	if (!aux->transfer)
 		return;
 
+	if (aux->is_remote) {
+		schedule_work(&aux->cec.mst_irq_work);
+		return;
+	}
 	mutex_lock(&aux->cec.lock);
 	if (!aux->cec.adap)
 		goto unlock;
@@ -276,6 +281,24 @@ static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap)
 	return true;
 }
 
+static void drm_dp_cec_mst_irq_work(struct work_struct *work)
+{
+	struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux,
+					      cec.mst_irq_work);
+	struct drm_dp_mst_port *port =
+		container_of(aux, struct drm_dp_mst_port, aux);
+
+	port = drm_dp_mst_topology_get_port_validated(port->mgr, port);
+	if (!port)
+		return;
+	mutex_lock(&aux->cec.lock);
+	if (aux->cec.adap)
+		drm_dp_cec_handle_irq(aux);
+
+	mutex_unlock(&aux->cec.lock);
+	drm_dp_mst_topology_put_port(port);
+}
+
 /*
  * Called if the HPD was low for more than drm_dp_cec_unregister_delay
  * seconds. This unregisters the CEC adapter.
@@ -297,7 +320,8 @@ static void drm_dp_cec_unregister_work(struct work_struct *work)
  * were unchanged and just update the CEC physical address. Otherwise
  * unregister the old CEC adapter and create a new one.
  */
-void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
+static void drm_dp_cec_handle_set_edid(struct drm_dp_aux *aux,
+				       const struct edid *edid)
 {
 	struct drm_connector *connector = aux->cec.connector;
 	u32 cec_caps = CEC_CAP_DEFAULTS | CEC_CAP_NEEDS_HPD |
@@ -306,10 +330,6 @@ void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
 	unsigned int num_las = 1;
 	u8 cap;
 
-	/* No transfer function was set, so not a DP connector */
-	if (!aux->transfer)
-		return;
-
 #ifndef CONFIG_MEDIA_CEC_RC
 	/*
 	 * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by
@@ -320,6 +340,7 @@ void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
 	 */
 	cec_caps &= ~CEC_CAP_RC;
 #endif
+	cancel_work_sync(&aux->cec.mst_irq_work);
 	cancel_delayed_work_sync(&aux->cec.unregister_work);
 
 	mutex_lock(&aux->cec.lock);
@@ -375,6 +396,18 @@ void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
 unlock:
 	mutex_unlock(&aux->cec.lock);
 }
+
+void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
+{
+	/* No transfer function was set, so not a DP connector */
+	if (!aux->transfer)
+		return;
+
+	if (aux->is_remote)
+		schedule_work(&aux->cec.mst_set_edid_work);
+	else
+		drm_dp_cec_handle_set_edid(aux, edid);
+}
 EXPORT_SYMBOL(drm_dp_cec_set_edid);
 
 /*
@@ -393,6 +426,8 @@ void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
 		goto unlock;
 
 	cec_phys_addr_invalidate(aux->cec.adap);
+	cancel_work_sync(&aux->cec.mst_irq_work);
+
 	/*
 	 * We're done if we want to keep the CEC device
 	 * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the
@@ -414,6 +449,26 @@ void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
 }
 EXPORT_SYMBOL(drm_dp_cec_unset_edid);
 
+static void drm_dp_cec_mst_set_edid_work(struct work_struct *work)
+{
+	struct drm_dp_aux *aux =
+		container_of(work, struct drm_dp_aux, cec.mst_set_edid_work);
+	struct drm_dp_mst_port *port =
+		container_of(aux, struct drm_dp_mst_port, aux);
+	struct edid *edid = NULL;
+
+	port = drm_dp_mst_topology_get_port_validated(port->mgr, port);
+	if (!port)
+		return;
+
+	edid = drm_get_edid(port->connector, &port->aux.ddc);
+
+	if (edid)
+		drm_dp_cec_handle_set_edid(aux, edid);
+
+	drm_dp_mst_topology_put_port(port);
+}
+
 /**
  * drm_dp_cec_register_connector() - register a new connector
  * @aux: DisplayPort AUX channel
@@ -433,6 +488,8 @@ void drm_dp_cec_register_connector(struct drm_dp_aux *aux,
 	aux->cec.connector = connector;
 	INIT_DELAYED_WORK(&aux->cec.unregister_work,
 			  drm_dp_cec_unregister_work);
+	INIT_WORK(&aux->cec.mst_irq_work, drm_dp_cec_mst_irq_work);
+	INIT_WORK(&aux->cec.mst_set_edid_work, drm_dp_cec_mst_set_edid_work);
 }
 EXPORT_SYMBOL(drm_dp_cec_register_connector);
 
@@ -442,6 +499,8 @@ EXPORT_SYMBOL(drm_dp_cec_register_connector);
  */
 void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux)
 {
+	cancel_work_sync(&aux->cec.mst_irq_work);
+	cancel_work_sync(&aux->cec.mst_set_edid_work);
 	if (!aux->cec.adap)
 		return;
 	cancel_delayed_work_sync(&aux->cec.unregister_work);
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index c783a2a1c114..221c30133739 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2183,6 +2183,8 @@ static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
 int drm_dp_mst_connector_late_register(struct drm_connector *connector,
 				       struct drm_dp_mst_port *port)
 {
+	drm_dp_cec_register_connector(&port->aux, connector);
+
 	DRM_DEBUG_KMS("registering %s remote bus for %s\n",
 		      port->aux.name, connector->kdev->kobj.name);
 
@@ -2206,6 +2208,8 @@ void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
 	DRM_DEBUG_KMS("unregistering %s remote bus for %s\n",
 		      port->aux.name, connector->kdev->kobj.name);
 	drm_dp_aux_unregister_devnode(&port->aux);
+
+	drm_dp_cec_unregister_connector(&port->aux);
 }
 EXPORT_SYMBOL(drm_dp_mst_connector_early_unregister);
 
@@ -2515,6 +2519,21 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb,
 		queue_work(system_long_wq, &mstb->mgr->work);
 }
 
+static void
+drm_dp_mst_handle_sink_event(struct drm_dp_mst_branch *mstb,
+			    struct drm_dp_sink_event_notify *sink_event)
+{
+	struct drm_dp_mst_port *port;
+
+	if (sink_event->event_id & DP_SINK_EVENT_CEC_IRQ_EVENT) {
+		port = drm_dp_get_port(mstb, sink_event->port_number);
+		if (port) {
+			drm_dp_cec_irq(&port->aux);
+			drm_dp_mst_topology_put_port(port);
+		}
+	}
+}
+
 static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
 							       u8 lct, u8 *rad)
 {
@@ -3954,6 +3973,8 @@ drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr,
 	if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY) {
 		drm_dp_mst_handle_conn_stat(mstb, &msg->u.conn_stat);
 		hotplug = true;
+	} else if (msg->req_type == DP_SINK_EVENT_NOTIFY) {
+		drm_dp_mst_handle_sink_event(mstb, &msg->u.sink_event);
 	}
 
 	drm_dp_mst_topology_put_mstb(mstb);
@@ -4147,6 +4168,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
 		break;
 	}
 out:
+	if (ret != connector_status_connected)
+		drm_dp_cec_unset_edid(&port->aux);
 	drm_dp_mst_topology_put_port(port);
 	return ret;
 }
@@ -4177,6 +4200,7 @@ struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_
 		edid = drm_get_edid(connector, &port->aux.ddc);
 	}
 	port->has_audio = drm_detect_monitor_audio(edid);
+	drm_dp_cec_set_edid(&port->aux, edid);
 	drm_dp_mst_topology_put_port(port);
 	return edid;
 }
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 85513eeb2196..d8ee24a6319c 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1496,12 +1496,16 @@ struct drm_connector;
  * @adap: the CEC adapter for CEC-Tunneling-over-AUX support.
  * @connector: the connector this CEC adapter is associated with
  * @unregister_work: unregister the CEC adapter
+ * @mst_irq_work: IRQ for CEC events on an MST branch
+ * @mst_set_edid_work: set the EDID for an MST branch
  */
 struct drm_dp_aux_cec {
 	struct mutex lock;
 	struct cec_adapter *adap;
 	struct drm_connector *connector;
 	struct delayed_work unregister_work;
+	struct work_struct mst_irq_work;
+	struct work_struct mst_set_edid_work;
 };
 
 /**
-- 
2.28.0.526.ge36021eeef-goog

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Re: [PATCH v2 4/4] drm_dp_cec: add MST support

[Hans Verkuil]

On 09/09/2020 09:20, Sam McNally wrote:
> With DP v2.0 errata E5, CEC tunneling can be supported through an MST
> topology.
> 
> There are some minor differences for CEC tunneling through an MST
> topology compared to CEC tunneling to an SST port:
> - CEC IRQs are delivered via a sink event notify message
> - CEC-related DPCD registers are accessed via remote DPCD reads and
>   writes.
> 
> This results in the MST implementation diverging from the existing SST
> implementation:
> - sink event notify messages with CEC_IRQ ID set indicate CEC IRQ rather
>   than ESI1
> - setting edid and handling CEC IRQs, which can be triggered from
>   contexts where locks held preclude HPD handling, are deferred to avoid
>   remote DPCD access which would block until HPD handling is performed
>   or a timeout
> 
> Register and unregister for all MST connectors, ensuring their
> drm_dp_aux_cec struct won't be accessed uninitialized.
> 
> Signed-off-by: Sam McNally <sammc@chromium.org>
> ---
> 
> Changes in v2:
> - Used aux->is_remote instead of aux->cec.is_mst, removing the need for
>   the previous patch in the series
> - Added a defensive check for null edid in the deferred set_edid work,
>   in case the edid is no longer valid at that point
> 
>  drivers/gpu/drm/drm_dp_cec.c          | 69 +++++++++++++++++++++++++--
>  drivers/gpu/drm/drm_dp_mst_topology.c | 24 ++++++++++
>  include/drm/drm_dp_helper.h           |  4 ++
>  3 files changed, 92 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c
> index 3ab2609f9ec7..d708fc1e273a 100644
> --- a/drivers/gpu/drm/drm_dp_cec.c
> +++ b/drivers/gpu/drm/drm_dp_cec.c
> @@ -14,6 +14,7 @@
>  #include <drm/drm_connector.h>
>  #include <drm/drm_device.h>
>  #include <drm/drm_dp_helper.h>
> +#include <drm/drm_dp_mst_helper.h>
>  
>  /*
>   * Unfortunately it turns out that we have a chicken-and-egg situation
> @@ -248,6 +249,10 @@ void drm_dp_cec_irq(struct drm_dp_aux *aux)
>  	if (!aux->transfer)
>  		return;
>  
> +	if (aux->is_remote) {
> +		schedule_work(&aux->cec.mst_irq_work);
> +		return;
> +	}
>  	mutex_lock(&aux->cec.lock);
>  	if (!aux->cec.adap)
>  		goto unlock;
> @@ -276,6 +281,24 @@ static bool drm_dp_cec_cap(struct drm_dp_aux *aux, u8 *cec_cap)
>  	return true;
>  }
>  
> +static void drm_dp_cec_mst_irq_work(struct work_struct *work)
> +{
> +	struct drm_dp_aux *aux = container_of(work, struct drm_dp_aux,
> +					      cec.mst_irq_work);
> +	struct drm_dp_mst_port *port =
> +		container_of(aux, struct drm_dp_mst_port, aux);
> +
> +	port = drm_dp_mst_topology_get_port_validated(port->mgr, port);
> +	if (!port)
> +		return;
> +	mutex_lock(&aux->cec.lock);
> +	if (aux->cec.adap)
> +		drm_dp_cec_handle_irq(aux);
> +

As mentioned in my first review: this empty line makes the code look unbalanced since
there is no corresponding empty line after the mutex_lock.

I think it should just be removed and optionally an empty line can be added before the
mutex_lock.

> +	mutex_unlock(&aux->cec.lock);
> +	drm_dp_mst_topology_put_port(port);
> +}
> +
>  /*
>   * Called if the HPD was low for more than drm_dp_cec_unregister_delay
>   * seconds. This unregisters the CEC adapter.
> @@ -297,7 +320,8 @@ static void drm_dp_cec_unregister_work(struct work_struct *work)
>   * were unchanged and just update the CEC physical address. Otherwise
>   * unregister the old CEC adapter and create a new one.
>   */
> -void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
> +static void drm_dp_cec_handle_set_edid(struct drm_dp_aux *aux,
> +				       const struct edid *edid)
>  {
>  	struct drm_connector *connector = aux->cec.connector;
>  	u32 cec_caps = CEC_CAP_DEFAULTS | CEC_CAP_NEEDS_HPD |
> @@ -306,10 +330,6 @@ void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
>  	unsigned int num_las = 1;
>  	u8 cap;
>  
> -	/* No transfer function was set, so not a DP connector */
> -	if (!aux->transfer)
> -		return;
> -
>  #ifndef CONFIG_MEDIA_CEC_RC
>  	/*
>  	 * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by
> @@ -320,6 +340,7 @@ void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
>  	 */
>  	cec_caps &= ~CEC_CAP_RC;
>  #endif
> +	cancel_work_sync(&aux->cec.mst_irq_work);
>  	cancel_delayed_work_sync(&aux->cec.unregister_work);
>  
>  	mutex_lock(&aux->cec.lock);
> @@ -375,6 +396,18 @@ void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
>  unlock:
>  	mutex_unlock(&aux->cec.lock);
>  }
> +
> +void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
> +{
> +	/* No transfer function was set, so not a DP connector */
> +	if (!aux->transfer)
> +		return;
> +
> +	if (aux->is_remote)
> +		schedule_work(&aux->cec.mst_set_edid_work);
> +	else
> +		drm_dp_cec_handle_set_edid(aux, edid);
> +}
>  EXPORT_SYMBOL(drm_dp_cec_set_edid);
>  
>  /*
> @@ -393,6 +426,8 @@ void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
>  		goto unlock;
>  
>  	cec_phys_addr_invalidate(aux->cec.adap);
> +	cancel_work_sync(&aux->cec.mst_irq_work);
> +
>  	/*
>  	 * We're done if we want to keep the CEC device
>  	 * (drm_dp_cec_unregister_delay is >= NEVER_UNREG_DELAY) or if the
> @@ -414,6 +449,26 @@ void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
>  }
>  EXPORT_SYMBOL(drm_dp_cec_unset_edid);
>  
> +static void drm_dp_cec_mst_set_edid_work(struct work_struct *work)
> +{
> +	struct drm_dp_aux *aux =
> +		container_of(work, struct drm_dp_aux, cec.mst_set_edid_work);
> +	struct drm_dp_mst_port *port =
> +		container_of(aux, struct drm_dp_mst_port, aux);
> +	struct edid *edid = NULL;
> +
> +	port = drm_dp_mst_topology_get_port_validated(port->mgr, port);
> +	if (!port)
> +		return;
> +
> +	edid = drm_get_edid(port->connector, &port->aux.ddc);
> +
> +	if (edid)
> +		drm_dp_cec_handle_set_edid(aux, edid);
> +
> +	drm_dp_mst_topology_put_port(port);
> +}
> +

Please move this function to before the drm_dp_cec_unset_edid() function.
That way all set_edid related functions are grouped together.

>  /**
>   * drm_dp_cec_register_connector() - register a new connector
>   * @aux: DisplayPort AUX channel
> @@ -433,6 +488,8 @@ void drm_dp_cec_register_connector(struct drm_dp_aux *aux,
>  	aux->cec.connector = connector;
>  	INIT_DELAYED_WORK(&aux->cec.unregister_work,
>  			  drm_dp_cec_unregister_work);
> +	INIT_WORK(&aux->cec.mst_irq_work, drm_dp_cec_mst_irq_work);
> +	INIT_WORK(&aux->cec.mst_set_edid_work, drm_dp_cec_mst_set_edid_work);
>  }
>  EXPORT_SYMBOL(drm_dp_cec_register_connector);
>  
> @@ -442,6 +499,8 @@ EXPORT_SYMBOL(drm_dp_cec_register_connector);
>   */
>  void drm_dp_cec_unregister_connector(struct drm_dp_aux *aux)
>  {
> +	cancel_work_sync(&aux->cec.mst_irq_work);
> +	cancel_work_sync(&aux->cec.mst_set_edid_work);
>  	if (!aux->cec.adap)
>  		return;
>  	cancel_delayed_work_sync(&aux->cec.unregister_work);
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index c783a2a1c114..221c30133739 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -2183,6 +2183,8 @@ static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
>  int drm_dp_mst_connector_late_register(struct drm_connector *connector,
>  				       struct drm_dp_mst_port *port)
>  {
> +	drm_dp_cec_register_connector(&port->aux, connector);
> +
>  	DRM_DEBUG_KMS("registering %s remote bus for %s\n",
>  		      port->aux.name, connector->kdev->kobj.name);
>  
> @@ -2206,6 +2208,8 @@ void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
>  	DRM_DEBUG_KMS("unregistering %s remote bus for %s\n",
>  		      port->aux.name, connector->kdev->kobj.name);
>  	drm_dp_aux_unregister_devnode(&port->aux);
> +
> +	drm_dp_cec_unregister_connector(&port->aux);
>  }
>  EXPORT_SYMBOL(drm_dp_mst_connector_early_unregister);
>  
> @@ -2515,6 +2519,21 @@ drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb,
>  		queue_work(system_long_wq, &mstb->mgr->work);
>  }
>  
> +static void
> +drm_dp_mst_handle_sink_event(struct drm_dp_mst_branch *mstb,
> +			    struct drm_dp_sink_event_notify *sink_event)
> +{
> +	struct drm_dp_mst_port *port;
> +
> +	if (sink_event->event_id & DP_SINK_EVENT_CEC_IRQ_EVENT) {
> +		port = drm_dp_get_port(mstb, sink_event->port_number);
> +		if (port) {
> +			drm_dp_cec_irq(&port->aux);
> +			drm_dp_mst_topology_put_port(port);
> +		}
> +	}
> +}
> +
>  static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
>  							       u8 lct, u8 *rad)
>  {
> @@ -3954,6 +3973,8 @@ drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr,
>  	if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY) {
>  		drm_dp_mst_handle_conn_stat(mstb, &msg->u.conn_stat);
>  		hotplug = true;
> +	} else if (msg->req_type == DP_SINK_EVENT_NOTIFY) {
> +		drm_dp_mst_handle_sink_event(mstb, &msg->u.sink_event);
>  	}
>  
>  	drm_dp_mst_topology_put_mstb(mstb);
> @@ -4147,6 +4168,8 @@ drm_dp_mst_detect_port(struct drm_connector *connector,
>  		break;
>  	}
>  out:
> +	if (ret != connector_status_connected)
> +		drm_dp_cec_unset_edid(&port->aux);
>  	drm_dp_mst_topology_put_port(port);
>  	return ret;
>  }
> @@ -4177,6 +4200,7 @@ struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_
>  		edid = drm_get_edid(connector, &port->aux.ddc);
>  	}
>  	port->has_audio = drm_detect_monitor_audio(edid);
> +	drm_dp_cec_set_edid(&port->aux, edid);
>  	drm_dp_mst_topology_put_port(port);
>  	return edid;
>  }
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 85513eeb2196..d8ee24a6319c 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -1496,12 +1496,16 @@ struct drm_connector;
>   * @adap: the CEC adapter for CEC-Tunneling-over-AUX support.
>   * @connector: the connector this CEC adapter is associated with
>   * @unregister_work: unregister the CEC adapter
> + * @mst_irq_work: IRQ for CEC events on an MST branch
> + * @mst_set_edid_work: set the EDID for an MST branch
>   */
>  struct drm_dp_aux_cec {
>  	struct mutex lock;
>  	struct cec_adapter *adap;
>  	struct drm_connector *connector;
>  	struct delayed_work unregister_work;
> +	struct work_struct mst_irq_work;
> +	struct work_struct mst_set_edid_work;
>  };
>  
>  /**
> 

With those two small issues corrected:

Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Regards,

	Hans
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