On Mon, Jan 21, 2013 at 10:18:06PM +0800, Lan Tianyu wrote:
> 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);
Oh, I don't see any code calling this function, so why did you add it?
Who needs it? Where is that code?
thanks,
greg k-h
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