From: Mike Ditto <mditto@consentry.com>
To: Jochen Friedrich <jochen@scram.de>,
David Gibson <david@gibson.dropbear.id.au>
Cc: linuxppc-dev@ozlabs.org, i2c@lm-sensors.org
Subject: Re: [PATCH] i2c-cpm: Add flexibility for I2C clock frequency and filter.
Date: Wed, 05 Nov 2008 16:35:03 -0800 [thread overview]
Message-ID: <49123BB7.90503@consentry.com> (raw)
In-Reply-To: <20081105233617.GC28465@yookeroo.seuss>
David Gibson wrote:
> What does worry me, however, is the description says it's about
> whether the driver "should" enable the filter. Generally the device
> tree doesn't attempt to say what users "should" do with the hardware,
> just what the characteristics of the hardware are.
>
> What's the underlying difference here that affects the driver's choice
> to enable the filter or not?
I think it's a hardware/environment design parameter - e.g. if the I2C
bus has hot-pluggable devices, long PCB traces, or a hierarchy of
multiplexed bus segments, these can result in a noisy SCL signal that
needs to be filtered. It's also a recommended mitigation for errata
in certain CPU revs.
-=] Mike [=-
next prev parent reply other threads:[~2008-11-06 0:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-31 4:09 [PATCH] i2c-cpm: Add flexibility for I2C clock frequency and filter Mike Ditto
2008-10-31 11:40 ` Jochen Friedrich
2008-10-31 21:19 ` Mike Ditto
2008-10-31 21:22 ` Mike Ditto
2008-11-05 23:36 ` David Gibson
2008-11-06 0:35 ` Mike Ditto [this message]
2008-11-06 0:53 ` David Gibson
2008-11-06 1:12 ` Mike Ditto
-- strict thread matches above, loose matches on Subject: below --
2008-10-31 4:13 Mike Ditto
2008-11-06 1:55 Mike Ditto
2008-11-06 11:27 ` Jochen Friedrich
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