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.
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
---
drivers/usb/core/port.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index 0c51d24..0334d91 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -18,11 +18,39 @@
#include <linux/slab.h>
#include <linux/pm_qos.h>
+#include <linux/module.h>
#include "hub.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)
{
--
1.7.9.5
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