Re: [PATCH] USB: serial: use tty_port_register_device_serdev

["Måns Rullgård" <mans@mansr.com>]

Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:

> On Thu, May 02, 2024 at 11:45:44AM +0100, Måns Rullgård wrote:
>> Johan Hovold <johan@kernel.org> writes:
>> 
>> > On Thu, May 02, 2024 at 11:07:28AM +0100, Mans Rullgard wrote:
>> >> Use tty_port_register_device_serdev() so that usb-serial devices
>> >> can be used as serdev controllers.
>> >
>> > I'm afraid it's not that easy. The reason serdev is not enabled for
>> > usb-serial is that there's currently no support for handling hotplug in
>> > serdev. The device can go away from under you at any time and then you'd
>> > crash the kernel.
>> 
>> Oh, that's unfortunate.  Regular serial ports can go away too, though,
>> and that seems to be handled fine.  What am I missing?
>
> How is it handled?  Normal serial ports can go away but in practice,
> it's a rare occurance, and usually people use serdev for devices where
> the ports can not be removed (i.e. internal connections).

If I unbind a regular serial port from its driver using sysfs, a serdev
device defined in a device tree gets removed as expected.  Binding the
serial port makes everything come back again.  I fail to see any problem
here.  If there is one, you'll have to be less evasive in explaining
what it is.

-- 
Måns Rullgård