Re: [PATCH 3/4] devicetree: bindings: Add defeature-repeated-start property for Cadence I2C

From: Wolfram Sang
Date: Tue Dec 02 2014 - 08:16:30 EST



> But given the bugs, it will be useful to just disable it if the system doesn't
> require repeated start.

What do you do when disable repeated start? Sending STOP and START? If
so, this is really something different than repeated start. By using
I2C_FUNC_I2C a user expects repeated start, so if the HW does not
support it, we should say so and don't try to emulate it with something
different.

> If you think DT entry is not the way to go, do you think a CONFIG option or
> something better will work?

No, check at runtime if the transfer is possible on this HW. Bail out if
not.

> We chose a DT property because there is a good chance the user has multiple
> cadence I2C controllers - one connected to a slave that needs repeated start
> (like a power controller) and another that doesn't care.

The user should not need to know with this level of detail if we can
avoid it IMO.

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