[PATCH] i2c-cpm: Add flexibility for I2C clock frequency and filter.
Mike Ditto
mditto at consentry.com
Thu Nov 6 11:35:03 EST 2008
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 [=-
More information about the Linuxppc-dev
mailing list