On Sat, 5 Jan 2013, Lan Tianyu wrote:
> 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.
I was thinking more of something like this. In port.c:
int usb_device_allow_prevent_power_off(struct usb_device *udev, bool allow)
{
...
}
In include/linux/usb.h:
static int inline usb_device_allow_power_off(struct usb_device *udev)
{
return usb_device_allow_prevent_power_off(udev, true);
}
static int inline usb_device_prevent_power_off(struct usb_device *udev)
{
return usb_device_allow_prevent_power_off(udev, false);
}
Alan Stern
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