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:
> > BO will disable USB input until the device opens. This will
> > avoid garbage chars waiting flood the TTY. This mimics a real UART
> > device better.
> > For initial termios to reach USB core, USB driver has to be
> > registered before TTY driver.
>
> You are doing two different things here, please break this up into 2
> patches, with good documentation for both of them.
>
> And any reason you didn't send this to the people listed in
> scripts/get_maintainers.pl when run on this patch?
>
> >
> > Signed-off-by: Joakim Tjernlund <joakim.tjernlund@xxxxxxxxxxxx>
> > Cc: stable@xxxxxxxxxxxxxxx
> > ---
> >
> > I hope this change makes sense to you, if so I belive
> > ttyUSB could do the same.
> >
> > drivers/usb/class/cdc-acm.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
> > index 751f00285ee6..5680f71200e5 100644
> > --- a/drivers/usb/class/cdc-acm.c
> > +++ b/drivers/usb/class/cdc-acm.c
> > @@ -1999,19 +1999,19 @@ static int __init acm_init(void)
> > acm_tty_driver->subtype = SERIAL_TYPE_NORMAL,
> > acm_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
> > acm_tty_driver->init_termios = tty_std_termios;
> > - acm_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD |
> > + acm_tty_driver->init_termios.c_cflag = B0 | CS8 | CREAD |
> > HUPCL | CLOCAL;
>
> Huh? Are you sure this works?
Yes, sort of. I didn't see prehistory chars when changed to B0
>
> > 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?
I could change to:
cdc-acm: acm_init: register USB before TTY driver
For initial termios to reach USB core, USB driver has to be
registered before TTY driver.
and then just have that change:
@@ -2003,15 +2003,15 @@ static int __init acm_init(void)
HUPCL | CLOCAL;
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);
put_tty_driver(acm_tty_driver);
return retval;
}
