From: Wolfgang Grandegger <wg@grandegger.com>
To: Felix Radensky <felix@embedded-sol.com>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: I2C bus clock on MPC85XX systems
Date: Tue, 22 Dec 2009 17:18:45 +0100 [thread overview]
Message-ID: <4B30F165.2060300@grandegger.com> (raw)
In-Reply-To: <4B30E7F5.8080201@embedded-sol.com>
Felix Radensky wrote:
> Hi,
>
> Almost all MPC85XX based systems have the compatible=:"fsl-i2c" in
> respective
> i2c device tree nodes. This causes FSL i2c driver to use the following
> "backward
> compatible" values: FSR=0x31 DFSR=0x10. This is regardless of CCB clock
> frequency and i2c clock prescaler.
>
> On my custom MPC8536 based board with 432MHz CCB clock this results in
> 65KHz i2c clock frequency (checked with scope). U-Boot correctly configures
> the clock to 400KHz.
>
> I've fixed the problem by modifying device tree to use different
> compatible value,
> similar to what socrates board does. Is this the right approach ?
Are you aware of the properties described in
"Documentation/powerpc/dts-bindings/fsl/i2c.txt":
http://lxr.linux.no/#linux+v2.6.32/Documentation/powerpc/dts-bindings/fsl/i2c.txt
Wolfgang.
next prev parent reply other threads:[~2009-12-22 16:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-22 15:38 I2C bus clock on MPC85XX systems Felix Radensky
2009-12-22 16:18 ` Wolfgang Grandegger [this message]
2009-12-22 18:16 ` Felix Radensky
2009-12-22 18:40 ` Wolfgang Grandegger
2009-12-22 19:06 ` Felix Radensky
2009-12-22 19:20 ` Wolfgang Grandegger
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=4B30F165.2060300@grandegger.com \
--to=wg@grandegger.com \
--cc=felix@embedded-sol.com \
--cc=linuxppc-dev@ozlabs.org \
/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.