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Message-ID: <669779.38970.qm@web94901.mail.in2.yahoo.com>
Date: Wed, 24 Mar 2010 23:02:51 +0530 (IST)
From: Pavan Savoy <pavan_savoy@...oo.co.in>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
Cc: Marcel Holtmann <marcel@...tmann.org>, Greg KH <gregkh@...e.de>,
PavanSavoy <pavan_savoy@...com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/6] drivers:misc: sources for Init manager module
--- On Wed, 24/3/10, Alan Cox <alan@...rguk.ukuu.org.uk> wrote:
> From: Alan Cox <alan@...rguk.ukuu.org.uk>
> Subject: Re: [PATCH 4/6] drivers:misc: sources for Init manager module
> To: "Pavan Savoy" <pavan_savoy@...oo.co.in>
> Cc: "Marcel Holtmann" <marcel@...tmann.org>, "Greg KH" <gregkh@...e.de>, "PavanSavoy" <pavan_savoy@...com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
> Date: Wednesday, 24 March, 2010, 10:56 PM
> > Isn't there a mechanism for the
> tty_set_ldisc to do what _open does ?
> > I mean there might be plenty of devices on UART which
> might not need /dev/tty at all ? i.e An App need not open
> for a ldisc to be installed.
>
> There is no mechanism to have an open tty without having an
> open file
> attached to it - and changing that would be very very non
> trivial. Plus
> you still need a way to tell the kernel you want the device
> in question
> active. That probably should get addressed some day but its
> not a quick
> fix up!
Which puts me back to square 1, the requirement is TTY device should be open, only when either BT, FM or GPS would want to use it.
[with your patch one of the steps of installing ldisc would be reduced upon opening].
Now from kernel-space which is the first to get notification about requirement of BT/FM or GPS, I somehow have to communicate it to user-space, without the much disliked sysfs entry method.
How do I tell the user-space when I want the TTY device to be opened ?
Actually why do I even need a TTY device in this case - right ?
ldisc driver can do the tty->ops->write and tty_read and put it up on different interfaces like eth0/hci0 or /dev/radio0 etc..
That would mean, a device can be on UART, a ldisc driver attached to it, and doesn't require a user-space daemon to maintain the device node.
>
> Alan
>
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