From: Timur Tabi <timur@freescale.com>
To: rmcguire@videopresence.com
Cc: linuxppc-embedded@ozlabs.org
Subject: Re: DTS files, 83xx, clock frequencies
Date: Wed, 19 Dec 2007 09:14:17 -0600 [thread overview]
Message-ID: <47693549.9030105@freescale.com> (raw)
In-Reply-To: <000001c841ce$d11fcdd0$6405a8c0@absolut>
Russell McGuire wrote:
> Isn't default behavior that these fields are kept from the <BIOS> U-boot
> during boot, if a zero is present? Is there any advantage to resetting them
> within the dts file during linux boot up?
Depending on which version of U-Boot, a given property may or may not be
initialized by U-Boot. The problem is that as new properties are defined,
U-Boot is not always updated to initialize that property, and sometimes it's
only updated on some CPU families.
The qe/brg-frequency property is a good example. Prior to U-Boot 1.3, it was
not being initialized at all. With U-Boot 1.3, it's only initialized on 83xx,
even though some 85xx boards have a QE. I have a QE UART driver that looks at
qe/brg-frequency, and if it's non-zero, I use it. If it is zero, then I take
the qe/bus-frequency property and divide it in half.
--
Timur Tabi
Linux kernel developer at Freescale
prev parent reply other threads:[~2007-12-19 15:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.543.1198006353.17691.linuxppc-embedded@ozlabs.org>
2007-12-18 23:36 ` DTS files, 83xx, clock frequencies Russell McGuire
2007-12-18 23:59 ` Scott Wood
2007-12-19 15:14 ` Timur Tabi [this message]
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=47693549.9030105@freescale.com \
--to=timur@freescale.com \
--cc=linuxppc-embedded@ozlabs.org \
--cc=rmcguire@videopresence.com \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.