Some usb devices can't be resumed correctly after power off. This
patch is to add usb_device_allow_power_off() and usb_device_prevent_power_off()
for device's driver. Call pm_runtime_get_sync(portdev) to increase port's usage
count and then port will not be suspended. The device will not be powered off.
Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
---
drivers/usb/core/port.c | 28 ++++++++++++++++++++++++++++
include/linux/usb.h | 12 ++++++++++++
2 files changed, 40 insertions(+)
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index a44523e..1b1c95e 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -18,9 +18,37 @@
#include "hub.h"
#include <linux/pm_qos.h>
+#include <linux/module.h>
static const struct attribute_group *port_dev_group[];
+/**
+ * usb_device_control_power_off - Allow or prohibit power off device.
+ * @udev: target usb device
+ * @allow: choice of allow or prohibit
+ *
+ * Call pm_runtime_get/put_sync(portdev) to allow or prohibit target
+ * usb device to be powered off in the kernel. The operations of setting
+ * true and false should be couple. The default status is allowed.
+ */
+int usb_device_control_power_off(struct usb_device *udev, bool allow)
+{
+ struct usb_port *port_dev;
+
+ if (!udev->parent)
+ return -EINVAL;
+
+ port_dev = hdev_to_hub(udev->parent)->ports[udev->portnum - 1];
+
+ if (allow)
+ pm_runtime_put_sync(&port_dev->dev);
+ else
+ pm_runtime_get_sync(&port_dev->dev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(usb_device_control_power_off);
+
static ssize_t show_port_connect_type(struct device *dev,
struct device_attribute *attr, char *buf)
{
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 689b14b..db1bac2 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -581,6 +581,18 @@ 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_control_power_off(struct usb_device *udev,
+ bool allow);
+
+static inline int usb_device_allow_power_off(struct usb_device *udev)
+{
+ return usb_device_control_power_off(udev, true);
+}
+
+static inline int usb_device_prevent_power_off(struct usb_device *udev)
+{
+ return usb_device_control_power_off(udev, false);
+}
/**
* usb_hub_for_each_child - iterate over all child devices on the hub
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
