lkml.org 
[lkml]   [2015]   [Jan]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/3] TTY: add support for "tty slave" devices.
Hi!

> > > +Optional child node:
> > > +- a platform device listed as a child node will be probed and
> > > + powered-on whenever the tty is in use (open).
> > > +
> > > Example:
> > >
> > > uart@80230000 {
> >

> But some line disciplines don't really want the char_dev.
> N_MOUSE wants a serio device.
> N_HCI wants an HCI device
> N_GSM07010 wants 63 different tty char_devs.
> N_IRDA and N_PPP ultimately want a net_dev.
> etc.
>
> It would be really nice if the uart would register the line disciple as a
> child device, then the line discipline would register whatever it wants.

Yes.

> N_HCI activates (registers the hci dev) on HCIUARTSETPROTO ioctl. A child
> device would need a way to specify the protocol I resume.
> N_MOUSE activates on a 'read' on the tty - and deactivates when the read
> completes.
> N_GSM0710 activates immediately that the ldisc is activated, as does N_IRDA
> N_PPP seems to want a PPPIOCNEWUNIT ioctl to fully register.
>
> Doing any of these in a driver for a uart slave device would certainly be
> possible. I wonder if it is something we really want to do in the kernel
> though. What is the gain over providing sufficient information in the
> KOBJ_ADD uevent so that udev can do the required work in user-space?

Consistency. If you have bluetooth on USB, it automatically works,
without userspace help. If we have mouse on USB, it automatically
works, etc...

> However I do like the idea of having the UART probe the child instead of
> registering a tty. It could pass the tty_operations structure to the child,
> and the child could then register a tty with a slightly different
> tty_operations structure, allowing it to capture any operations that it wants
> to capture (such as open/close).
> I might try coding that and see what it looks like...

Lets have a look...
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


\
 
 \ /
  Last update: 2015-01-04 11:41    [W:0.082 / U:1.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site