On Tue, 22 May 2007, Pandita, Vikram wrote: > >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; > }
I understand. The problem is that hub_port_init() also returns -ENODEV under some circumstances where we don't want to break out of the loop. So either you should change the code shown above to return something else (for example -EBADE) or else you should change hub_port_init(). Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
