On 2013年01月04日 23:59, Alan Stern wrote:
> On Fri, 4 Jan 2013, Lan Tianyu wrote:
>
>> 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.
>
> There should be two separate APIs: usb_device_allow_power_off() and
> usb_device_prevent_power_off(). If you want, they can be implemented
> as inline routines that call a single handler.
>
Ok.
How about this?
struct device *usb_get_port_dev(struct usb_device *udev)
{
struct usb_port *port_dev;
if (!udev->parent)
return NULL;
port_dev = &hdev_to_hub(udev->parent)->ports[udev->portnum - 1];
return &port_dev->dev;
}
static int inline usb_device_allow_power_off(struct usb_device *udev)
{
struct device *dev = usb_get_port_dev(udev);
if(!dev)
return -ENODEV;
return pm_runtime_put_sync(dev);
}
static int inline usb_device_prevent_power_off(struct usb_device *udev)
{
struct device *dev = usb_get_port_dev(udev);
if(!dev)
return -ENODEV;
return pm_runtime_get_sync(dev);
}
usb_get_port_dev() locates in the driver/usb/core/port.c and
usb_device_allow/prevent_power_off() locate in the include/linux/usb.h.
> Alan Stern
>
--
Best regards
Tianyu Lan
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