Re: [RFC 0/4] TWL external controller support

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

On Mon, Jul 11, 2011 at 11:23:11AM +0300, Tero Kristo wrote:
> On Sat, 2011-07-09 at 12:56 +0200, Mark Brown wrote:
> > On Sat, Jul 09, 2011 at 01:40:08PM +0300, Felipe Balbi wrote:

> > I'm completely unable to identify an issue in the framework that this
> > patch addresses - the API already supports multiple devices supplying
> > regulators, it's extremely difficult to understand what motivates the
> > change.

> So if I understood the comments right, what you are saying is that I
> should probably implement a new regulator subset for the twl-regulator.
> I.e. we have currently TWL4030_ADJUSTABLE_LDO etc., so I could add a
> TWL4030_ADJUSTABLE_SMPS for example. These regulators would then use the

No.  Why do you want these regulators to have anything to do with the
TWL4030?

> appropriate interface according to board specific setup. How would you
> propose to use / register the alternate ops to access the omap_voltage
> layer from here though for set/get voltage?

I have no visibility of the omap_voltage layer.  If it's peering into
the internals of the regulator API or regulator drivers you've got a
fairly serious abstraction problem that someone needs to fix...

> The main thing is that VDD1 and VDD2 regulators in TWL4030 can be
> controlled through the typical TWL control interface (I2C), like the
> rest of the TWL regulators, or it can be controlled through the voltage
> processor interface which uses a dedicated I2C bus and is not accessible
> to anything but the voltage processor. The used interface can be

That's not too unusual in hardware terms.

> configured from the TWL side. The voltage processor support is currently
> provided by the omap platform code, and regulator code knows nothing
> about this. It might also be possible to do compile time switch for the
> interface here if that is acceptable, however a runtime interface for
> doing this would provide more flexibility.

This isn't making much sense to me, what is the relationship between
this and the other regulators you're adding these bodge interfaces for?
Why would you want to switch between the two modes at runtime and how
would anyone take the decision to do so?

If some of the TWL4030 regulators are controlled by something other than
the CPU in your system then the TWL4030 driver shouldn't be configured
to do anything with them except possibly provide read only access.