Let userspace discover what is keeping a port powered. Here are the
states and the actions userspace can take to enable port power off.
PORT=<port sysfs directory>
'active': attached child device is actively using the port
echo auto > $PORT/<child>/power/control
'pm_qos_no_power_off': child inactive, pm qos flag keeps power enabled
echo 0 > $PORT/power/pm_qos_no_power_off
'wakeup enabled': port kept powered to handle remote wakeup events
echo 0 > $PORT/<child>/power/wakeup
'persist disabled': child device may not cleanly recover from
suspend/resume cycle
echo 1 > $PORT/<child>/power/persist
'off': port power is off
Reading this file makes an attempt to settle in-flight pm_runtime
transitions.
Signed-off-by: Dan Williams <[email protected]>
---
Documentation/ABI/testing/sysfs-bus-usb | 19 ++++++++++
drivers/usb/core/port.c | 60 +++++++++++++++++++++++++++++--
2 files changed, 75 insertions(+), 4 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-usb
b/Documentation/ABI/testing/sysfs-bus-usb
index 1430f584b266..91bfcfcfbfe3 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -148,6 +148,25 @@ Description:
The file will read "hotplug", "wired" and "not used" if the
information is available, and "unknown" otherwise.
+What: /sys/bus/usb/devices/.../(hub interface)/portX/power/power_state
+Date: November 2013
+Contact: Dan Williams <[email protected]>
+Description:
+ There are several gating factors that prevent a usb_port
+ from being powered down. Let userspace discover what is
+ keeping a port powered.
+
+ 'active': attached child device is actively using the
+ port
+ 'pm_qos_no_power_off': child inactive, pm qos flag keeps
+ power enabled
+ 'wakeup enabled': child inactive, port kept powered to
+ handle remote wakeup events
+ 'persist disabled': child inactive, but child device
+ will not cleanly recover from a
+ suspend/resume cycle
+ 'off': port power is off
+
What: /sys/bus/usb/devices/.../power/usb2_lpm_l1_timeout
Date: May 2013
Contact: Mathias Nyman <[email protected]>
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 6f20c0c8fe34..f7d1cd8a97d3 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -152,6 +152,55 @@ struct device_type usb_port_device_type = {
.pm = &usb_port_pm_ops,
};
+#ifdef CONFIG_PM
+static ssize_t power_state_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ const char *state;
+ struct usb_port *port_dev = to_usb_port(dev);
+ struct usb_device *child = usb_port_get_child(port_dev);
+
+ if (child) {
+ pm_runtime_barrier(&child->dev);
+ put_device(&child->dev);
+ }
+
+ pm_runtime_barrier(dev);
+
+ if (pm_runtime_active(dev))
+ state = "active";
+ else
+ state = power_on_reason(port_dev);
+
+ if (!state)
+ state = "off";
+
+ return sprintf(buf, "%s\n", state);
+}
+static DEVICE_ATTR_RO(power_state);
+
+static int add_port_power_state(struct usb_port *port_dev)
+{
+ return sysfs_add_file_to_group(&port_dev->dev.kobj,
+ &dev_attr_power_state.attr,
+ power_group_name);
+}
+
+static void remove_port_power_state(struct usb_port *port_dev)
+{
+ sysfs_remove_file_from_group(&port_dev->dev.kobj,
+ &dev_attr_power_state.attr,
+ power_group_name);
+}
+#else
+static int add_port_power_state(struct usb_port *port_dev)
+{
+ return 0;
+}
+
+static void remove_port_power_state(struct usb_port *port_dev) { }
+#endif
+
int usb_hub_create_port_device(struct usb_hub *hub, int port1)
{
struct usb_port *port_dev = NULL;
@@ -174,6 +223,8 @@ int usb_hub_create_port_device(struct usb_hub *hub, int
port1)
if (retval)
goto error_register;
+ add_port_power_state(port_dev);
+
pm_runtime_set_active(&port_dev->dev);
/* It would be dangerous if user space couldn't
@@ -193,9 +244,10 @@ exit:
return retval;
}
-void usb_hub_remove_port_device(struct usb_hub *hub,
- int port1)
+void usb_hub_remove_port_device(struct usb_hub *hub, int port1)
{
- device_unregister(&hub->ports[port1 - 1]->dev);
-}
+ struct usb_port *port_dev = hub->ports[port1 - 1];
+ remove_port_power_state(port_dev);
+ device_unregister(&port_dev->dev);
+}
--
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