From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Paul Rolland <rol@as2917.net>
Cc: linux-kernel@vger.kernel.org, rol@as2917.net
Subject: Re: Linux 2.6.x - Serial port signalling not maintained when closing device
Date: Thu, 26 Mar 2009 08:14:31 +0000 [thread overview]
Message-ID: <20090326081431.0163e193@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <20090326084220.4def5652@tux.DEF.witbe.net>
> As far as I can see, I need to have an application that keeps /dev/ttyS0
> open for this to work. As soon as no application is using the port,
> everything goes down again.
Yes - the 2.6 kernel has the newer uart driver layer and is also
(throughout) much more aggressive about power management. You'll see the
same with magic electronic project parallel port hacks where the port is
turned off when the device file is not open.
> This is a significant change between 2.4.x and 2.6.x.
Only to your rather unusual use of things. For normal use the current
behaviour is far more correct.
> Is there a way to
> change 2.6.x behavior to go back to the 2.4.x ? When was this change
> introduce ?
Just keep the port open when you are using it. Even in 2.4 the driver
could have been unloaded on some setups if you didn't have a port open.
Alan
next prev parent reply other threads:[~2009-03-26 8:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-26 7:42 Paul Rolland
2009-03-26 8:14 ` Alan Cox [this message]
2009-03-26 15:57 ` Paul Fulghum
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090326081431.0163e193@lxorguk.ukuu.org.uk \
--to=alan@lxorguk.ukuu.org.uk \
--cc=linux-kernel@vger.kernel.org \
--cc=rol@as2917.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®