On Sun, 2016-03-20 at 18:09 +0100, Guido Trentalancia wrote:
> Hello.
>
> Considering that EM interference can last for a while (generally up to
> seconds), I am currently testing the following patch for module usbcore
> so that it is possible to specify an amount of time to wait before
> trying to re-enable a port that has been previously disabled by the hub
> (supposedly because of EM interference).
>
> Hopefully, setting the right positive value (for example, 2000
> milliseconds) would help overcome situations such as the following:
>
The idea seems sound to me, but the implementation is problematic.
> @@ -4960,6 +4967,7 @@ static void port_event(struct usb_hub *h
> if (!(portstatus & USB_PORT_STAT_ENABLE)
> && !connect_change && udev) {
> dev_err(&port_dev->dev, "disabled by hub (EMI?),
> re-enabling...\n");
> + msleep(emi_recover_timer);
You cannot just stall here for seconds.
Regards
Oliver
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