On Fri, Jul 10, 2020 at 04:05:29PM +0000, Joakim Tjernlund wrote:
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?
No, not until the tty device has been registered by the USB driver.
Anyhow, does it not make sense to have usb before tty as tty uses usb?
Nope, it's the other way round, and your change is therefore broken.
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 ?
No, their purposes are distinct and they cannot be merged.
Johan