Hi Oliver,
that would be a misconfiguration issue, however I think we can set an upper limit for the new parameter... Also consider that the other "initial_descriptor_timeout" parameter is not limited by an upper limit...
And by the way, I should preferably modify the patch so that it correctly documents Documentation/kernel-parameters.txt.
Regards,
Guido
Il 21 marzo 2016 09:52:39 CET, Oliver Neukum <oneukum@xxxxxxxx> ha scritto:
>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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