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Message-ID: <20250619000343.3299526-2-rdbabiera@google.com>
Date: Thu, 19 Jun 2025 00:03:40 +0000
From: RD Babiera <rdbabiera@...gle.com>
Cc: heikki.krogerus@...ux.intel.com, badhri@...gle.com,
gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
linux-kernel@...r.kernel.org, RD Babiera <rdbabiera@...gle.com>
Subject: [PATCH v1] usb: typec: altmodes/displayport: add irq_hpd to sysfs
Add irq_hpd sysfs node to displayport driver. This allows the userspace
to subscribe to irq events similar to how it can subscribe to changes in
hpd.
irq_hpd is read only and returns the number of irq events generated since
driver probe. pending_irq_hpd is added so that a sysfs_emit can be
generated if the HPD high event belonging to the same status message
is delayed until a successful configuration.
Signed-off-by: RD Babiera <rdbabiera@...gle.com>
Reviewed-by: Badhri Jagan Sridharan <badhri@...gle.com>
---
.../testing/sysfs-driver-typec-displayport | 10 +++++++
drivers/usb/typec/altmodes/displayport.c | 29 +++++++++++++++++++
2 files changed, 39 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-driver-typec-displayport b/Documentation/ABI/testing/sysfs-driver-typec-displayport
index 256c87c5219a..314acd54e13e 100644
--- a/Documentation/ABI/testing/sysfs-driver-typec-displayport
+++ b/Documentation/ABI/testing/sysfs-driver-typec-displayport
@@ -62,3 +62,13 @@ Description:
by VESA DisplayPort Alt Mode on USB Type-C Standard.
- 0 when HPD’s logical state is low (HPD_Low) as defined by
VESA DisplayPort Alt Mode on USB Type-C Standard.
+
+What: /sys/bus/typec/devices/.../displayport/irq_hpd
+Date: June 2025
+Contact: RD Babiera <rdbabiera@...gle.com>
+Description:
+ IRQ_HPD events are sent over the USB PD protocol in Status Update and
+ Attention messages. IRQ_HPD can only be asserted when HPD is high,
+ and is asserted when an IRQ_HPD has been issued since the last Status
+ Update. This is a read only node that returns the number of IRQ events
+ raised in the driver's lifetime.
diff --git a/drivers/usb/typec/altmodes/displayport.c b/drivers/usb/typec/altmodes/displayport.c
index b09b58d7311d..7a04bb101337 100644
--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -65,6 +65,13 @@ struct dp_altmode {
enum dp_state state;
bool hpd;
bool pending_hpd;
+ u32 irq_hpd_count;
+ /*
+ * hpd is mandatory for irq_hpd assertion, so irq_hpd also needs its own pending flag if
+ * both hpd and irq_hpd are asserted in the first Status Update before the pin assignment
+ * is configured.
+ */
+ bool pending_irq_hpd;
struct mutex lock; /* device lock */
struct work_struct work;
@@ -151,6 +158,7 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
{
bool configured = !!DP_CONF_GET_PIN_ASSIGN(dp->data.conf);
bool hpd = !!(dp->data.status & DP_STATUS_HPD_STATE);
+ bool irq_hpd = !!(dp->data.status & DP_STATUS_IRQ_HPD);
u8 con = DP_STATUS_CONNECTION(dp->data.status);
int ret = 0;
@@ -170,6 +178,9 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
dp->hpd = hpd;
dp->pending_hpd = true;
}
+ if (dp->hpd && dp->pending_hpd && irq_hpd) {
+ dp->pending_irq_hpd = true;
+ }
}
} else {
drm_connector_oob_hotplug_event(dp->connector_fwnode,
@@ -177,6 +188,10 @@ static int dp_altmode_status_update(struct dp_altmode *dp)
connector_status_disconnected);
dp->hpd = hpd;
sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
+ if (hpd && irq_hpd) {
+ dp->irq_hpd_count++;
+ sysfs_notify(&dp->alt->dev.kobj, "displayport", "irq_hpd");
+ }
}
return ret;
@@ -196,6 +211,11 @@ static int dp_altmode_configured(struct dp_altmode *dp)
connector_status_connected);
sysfs_notify(&dp->alt->dev.kobj, "displayport", "hpd");
dp->pending_hpd = false;
+ if (dp->pending_irq_hpd) {
+ dp->irq_hpd_count++;
+ sysfs_notify(&dp->alt->dev.kobj, "displayport", "irq_hpd");
+ dp->pending_irq_hpd = false;
+ }
}
return dp_altmode_notify(dp);
@@ -707,10 +727,19 @@ static ssize_t hpd_show(struct device *dev, struct device_attribute *attr, char
}
static DEVICE_ATTR_RO(hpd);
+static ssize_t irq_hpd_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ struct dp_altmode *dp = dev_get_drvdata(dev);
+
+ return sysfs_emit(buf, "%d\n", dp->irq_hpd_count);
+}
+static DEVICE_ATTR_RO(irq_hpd);
+
static struct attribute *displayport_attrs[] = {
&dev_attr_configuration.attr,
&dev_attr_pin_assignment.attr,
&dev_attr_hpd.attr,
+ &dev_attr_irq_hpd.attr,
NULL
};
base-commit: e04c78d86a9699d136910cfc0bdcf01087e3267e
--
2.50.0.rc2.701.gf1e915cc24-goog
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