On Wed, 6 Nov 2019, Kai-Heng Feng wrote:
> On Dell WD15 dock, sometimes USB ethernet cannot be detected after plugging
> cable to the ethernet port, the hub and roothub get runtime resumed and
> runtime suspended immediately:
> ...
> ...
>
> As Mathias pointed out, the hub enters Cold Attach Status state and
> requires a warm reset. However usb_reset_device() bails out early when
> the device is in suspended state, as its callers port_event() and
> hub_event() don't always resume the device.
>
> Since there's nothing wrong to reset a suspended device, allow
> usb_reset_device() to do so to solve the issue.
I was sure I remembered reading somewhere that suspended devices were
not allowed to be reset, but now I can't find that requirement anywhere
in the USB spec.
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> ---
> drivers/usb/core/hub.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index 05a2d51bdbe0..f0194fdbc9b8 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -5877,8 +5877,7 @@ int usb_reset_device(struct usb_device *udev)
> struct usb_host_config *config = udev->actconfig;
> struct usb_hub *hub = usb_hub_to_struct_hub(udev->parent);
>
> - if (udev->state == USB_STATE_NOTATTACHED ||
> - udev->state == USB_STATE_SUSPENDED) {
> + if (udev->state == USB_STATE_NOTATTACHED) {
> dev_dbg(&udev->dev, "device reset not allowed in state %d\n",
> udev->state);
> return -EINVAL;
You forgot to update the kerneldoc for this function.
Alan Stern
