Re: [PATCH v6 0/8] mfd: introduce a driver for LPSS devices on SPT

Rafael J. Wysocki
2015-07-27T21:22:01Z

On Monday, July 27, 2015 05:24:13 PM Lee Jones wrote:
> On Mon, 27 Jul 2015, Mika Westerberg wrote:
>
> > On Mon, Jul 27, 2015 at 04:27:33PM +0100, Lee Jones wrote:
> > > FAO Stephen Boyd,
> > >
> > > > Stephen, can you, please, have a look into patch 8 regarding to clock name
> > > > matching and other stuff Lee asked?
> > >
> > > Patch 8:
> > >
> > > "Can you review the clock implementation please? It looks
> > > fragile to me as it relies heavily on device names constructed
> > > of MFD cell names and IDA numbers cat'ed together!"
> >
> > Lee, can you suggest an alternative then?
> >
> > Why we are doing it like this is that number of different LPSS devices
> > changes from SoC to SoC. In addition to that the device (called "slice")
> > might have iDMA block or not.
> >
> > Since the drivers in question (pxa2xx-spi, i2c-designware and 8250_dw)
> > use standard clk framework to request their clocks the Linux device must
> > have clock registered which matches the device in advance.
> >
> > Because we add the host controller device dynamically (from the MFD
> > driver) based on how many devices are actually present, we need somehow
> > predict what would be the correct name and instance number for that
> > device to get the clock for it. That's the reason we use IDA here along
> > with the cell name (or driver name).
>
> I'm sure there are perfectly viable reasons for you doing this. And I
> don't know the CCF well enough to know whether it's the best idea or
> not, or else I would have made a suggestion rather than waiting all
> this time.
>
> It's for this reason that I needed Mike (now Stephen) to take a look
> and give me either an Ack, to say it's the best solution, or to
> provide a better alternative.
>
> Until that happens, I'm stuck!

Well, what if we had no one at hand to review that code? Would that mean it
would not be applicable forever?

Thanks,
Rafael