On Fri, 2020-07-10 at 14:41 +0200, Johan Hovold wrote:
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> On Fri, Jul 10, 2020 at 10:46:19AM +0000, Joakim Tjernlund wrote:
> > On Fri, 2020-07-10 at 12:34 +0200, Greg KH wrote:
> > >
> > > On Fri, Jul 10, 2020 at 11:35:18AM +0200, Joakim Tjernlund wrote:
>
> > > > tty_set_operations(acm_tty_driver, &acm_ops);
> > > >
> > > > - retval = tty_register_driver(acm_tty_driver);
> > > > + retval = usb_register(&acm_driver);
> > > > if (retval) {
> > > > put_tty_driver(acm_tty_driver);
> > > > return retval;
> > > > }
> > > >
> > > > - retval = usb_register(&acm_driver);
> > > > + retval = tty_register_driver(acm_tty_driver);
> > > > if (retval) {
> > > > - tty_unregister_driver(acm_tty_driver);
> > > > + usb_deregister(&acm_driver);
> > >
> > > Why are you switching these around? I think I know, but you don't
> > > really say...
> >
> > I wrote:
> > For initial termios to reach USB core, USB driver has to be
> > registered before TTY driver.
> > Found out that by trial and error. Isn't that clear enough?
>
> No, that makes no sense at all since USB core does not care about
> init_termios.
But you install acm_ops into tty:
tty_set_operations(acm_tty_driver, &acm_ops);
Perhaps there is a call into acm_ops?
Anyhow, does it not make sense to have usb before tty as tty uses usb?
Can I ask this too:
what is the difference between acm_tty_install and acm_tty_open ? Both seems to be called at open(2)
seems to me that install could be folded into open ?
Jocke
