To: gregkh@xxxxxxxxxxxxxxxxxxx,
sarah.a.sharp@xxxxxxxxxxxxxxx,
stern@xxxxxxxxxxxxxxxxxxx,
rjw@xxxxxxx,
oneukum@xxxxxxx
Cc: linux-usb@xxxxxxxxxxxxxxx,
tianyu.lan@xxxxxxxxx,
sebastien.dufour@xxxxxxxxx
Some usb devices can't be resumed correctly after power off. This
patch is to add usb_device_allow_power_off() for device's driver to allow or
prohibit device to be power off the device. Call pm_runtime_get_sync(portdev)
to increase port's usage count and then port will not be suspended. The
device will not be power off.
Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
---
drivers/usb/core/hub.c | 28 ++++++++++++++++++++++++++++
include/linux/usb.h | 1 +
2 files changed, 29 insertions(+)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index acefb67..e53e371 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -135,6 +135,34 @@ struct usb_hub *hdev_to_hub(struct usb_device *hdev)
return usb_get_intfdata(hdev->actconfig->interface[0]);
}
+/**
+ * usb_device_allow_power_off - Allow or prohibit power off device.
+ * @udev: target usb device
+ * @set: choice of allow or prohibit
+ *
+ * Call pm_runtime_get/put_sync(portdev) to allow or prohibit target
+ * usb device to be power off in the kernel. The operations of setting
+ * true and false should be couple. The default status is allowed.
+ */
+int usb_device_allow_power_off(struct usb_device *udev, bool set)
+{
+ struct usb_port *port_dev;
+
+ if (!udev->parent)
+ return -EINVAL;
+
+ port_dev =
+ hdev_to_hub(udev->parent)->ports[udev->portnum - 1];
+
+ if (set)
+ pm_runtime_put_sync(&port_dev->dev);
+ else
+ pm_runtime_get_sync(&port_dev->dev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(usb_device_allow_power_off);
+
static int usb_device_supports_lpm(struct usb_device *udev)
{
/* USB 2.1 (and greater) devices indicate LPM support through
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 689b14b..e0b5f54 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -581,6 +581,7 @@ extern struct usb_device *usb_get_dev(struct usb_device *dev);
extern void usb_put_dev(struct usb_device *dev);
extern struct usb_device *usb_hub_find_child(struct usb_device *hdev,
int port1);
+extern int usb_device_allow_power_off(struct usb_device *udev, bool set);
/**
* usb_hub_for_each_child - iterate over all child devices on the hub
--
1.7.9.5
--
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