From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Paul Bolle <pebolle@tiscali.nl>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH][SERIAL] Drop probe_baud() and default to "9600n8"
Date: Tue, 7 Oct 2008 12:15:19 +0100 [thread overview]
Message-ID: <20081007121519.545fd5c7@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <1223377586.5129.43.camel@test.thuisdomein>
On Tue, 07 Oct 2008 13:06:26 +0200
Paul Bolle <pebolle@tiscali.nl> wrote:
> The early console kernel parameters (i.e. "console=uart[...]" and
> "earlycon=uart[...]" allow to omit the baud/parity/bits option. If that
> option is not provided probe_baud() is used to determine the baud rate
> to be used by that early console.
That depends a lot on the system.
> I noticed that probe_baud() produced useless and/or unpredictable
> results on the few machines I tested the early console parameters (e.g.
> 1355 or 1200 and 115200 alternating). My guess is that this is because
Depends on what the firmware has done. When the firmware has set the port
up as is common in embedded then it is a very useful option to continue
with the rates currently in use.
> probe_baud() and simply use "9600n8" as (safe) defaults for
> baud/parity/bits.
I don't plan to apply this change. If you can figure out a reliable way
to decide a port is uninitialised and default to 9600 in that case then
that would be interesting.
Alan
prev parent reply other threads:[~2008-10-07 11:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-07 11:06 Paul Bolle
2008-10-07 11:15 ` Alan Cox [this message]
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