Re: [PATCH v2 1/9] i2c: prepare runtime PM support for I2C client devices

[Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

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On Tue, Sep 17, 2013 at 03:25:25AM +0200, Rafael J. Wysocki wrote:
> On Tuesday, September 17, 2013 12:31:11 AM Mark Brown wrote:

> > It shouldn't even need to do that, it should just be able to rely on the
> > controller to power itself up when asked to do work.   This is how the
> > existing implementations are done - the controller power management is
> > totally transparent to the slave.

> If both the I2C client and I2C controller have corresponding objects in the
> ACPI namespace and the client's object is a child of the controller's object,
> then in order to power up the client we need to power up the controller even
> if no transactions are going to be carried out.  That's what the spec simply
> requires us to do in that case.

Like I said I think this should be handled by the power domains (or
otherwise in the ACPI specific code) - we shouldn't be needing to modify
individual drivers to work around thoughtlessness in the ACPI spec.

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