>From: Alan Stern [mailto:[EMAIL PROTECTED]
>On Mon, 21 May 2007, David Brownell wrote:
>> On Monday 21 May 2007, Vikram Pandita wrote:
>> > ---
>> > diff -purN -X ./dontdiff a/drivers/usb/core/hub.c
>> > b/drivers/usb/core/hub.c
>> > --- a/drivers/usb/core/hub.c 2007-05-13 14:24:43.000000000 +0530
>> > +++ b/drivers/usb/core/hub.c 2007-05-21 13:19:07.000000000 +0530
>> > @@ -2571,7 +2571,7 @@ loop:
>> > ep0_reinit(udev);
>> > release_address(udev);
>> > usb_put_dev(udev);
>> > - if (status == -ENOTCONN)
>> > + if ((status == -ENOTCONN) || (status == -ENODEV))
>> > break;
>> > }
>
>This is wrong. -ENOTCONN means what it says, that nothing is connected
>to the port. So when it occurs we really do want to break out of the
>loop.
>
>On the other hand, -ENODEV means that there is a device but it doesn't
>match our preconceptions (maybe its speed has somehow changed or some
>other aspect is different). Since there still is a device connected to
>the port, we don't want to break out of the loop.
>
>Did you notice any particular example where the port was unconnected
>and the code still tried to enumerate three times?
Yes. This is to fix the OTG HNP case.
In OTG enabled environment when the b-device attached is not supported
by host (is_targeted() returns Zero), the host suspends to give chance
to device to become b-host. If this fix is not in place, then the host
tries to enumerate the attached device SET_CONFIG_TRIES times which is
not required.
Following is the snippet of the code already in place that does the HNP
and returns the error code to stop re-enumerations and the proposed
patch checks for this error code:
if (!is_targeted(udev)) {
/* Maybe it can talk to us, though we can't talk to it.
* (Includes HNP test device.)
*/
if (udev->bus->b_hnp_enable || udev->bus->is_b_host) {
err = __usb_port_suspend(udev,
udev->bus->otg_port);
if (err < 0)
dev_dbg(&udev->dev, "HNP fail, %d\n",
err);
}
err = -ENODEV;
goto fail;
}
>
Vikram Pandita
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