[i2c] [patch 3/3] i2c: add support for i2c bus on Freescale CPM1/CPM2 controllers

[Trent Piepho]

On Mon, 2 Jun 2008, Ben Dooks wrote:
> makes reporting the amount of data written difficult, how do you
> indicate I wrote m bytes, got an error, and then continued on to
> write all n bytes of the i2c_msgs provided? Can anyone think of
> an actual example of where this would be useful?

Useful enough that someone would actually write the code to use it?  No.

> Yes, that does make sense to return the amount of data written to
> the user, however having a quick look through all users of
> i2c_transfer() all just want to know if all the messages where
> sent (which is an easier check that to compute the amount of
> data in all the messages).
>
> Would it better to add an new i2c_transfer-alike call which would
> return the amount of data written, instead of going around modifying
> all users of i2c_transfer() ? This would also make transfering from
> one call to the other, with i2c_transfer becoming deprecated?

My experience with I2C drivers is the same.  No one cares how many bytes
were written before a NAK, they're just going to take same failure path no
matter what (assuming they even check for an error at all).

I think it's enough to document the interface can't provide this
information, and if someone does have a real use for it in the future, let
them add support when the time comes.  There's no point in creating an
interface that no one is going to use.