Re: [PATCH v6 03/17] mfd: madera: Add common support for Cirrus Logic Madera codecs

[Richard Fitzgerald]

On 07/12/17 08:54, Linus Walleij wrote:
> On Mon, Dec 4, 2017 at 10:47 AM, Richard Fitzgerald
> <rf@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > On 02/12/17 12:10, Linus Walleij wrote:
> > > On Wed, Nov 29, 2017 at 12:36 PM, Richard Fitzgerald
> > > <rf@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > > > On 29/11/17 10:18, Linus Walleij wrote:
> > > > > On Thu, Nov 23, 2017 at 6:13 PM, Richard Fitzgerald
> > > > > <rf@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> > > > >
> > > > > > +config MFD_MADERA_I2C
> > > > > > +       bool "Cirrus Logic Madera codecs with I2C"
> > > > > > +       select MFD_MADERA
> > > > > > +       select REGMAP_I2C
> > > > > > +       depends on I2C
> > > > > > +       depends on PINCTRL
> > > > > > +       help
> > > > > > +         Support for the Cirrus Logic Madera platform audio SoC
> > > > > > +         core functionality controlled via I2C.
> > > > > > +
> > > > > > +config MFD_MADERA_SPI
> > > > > > +       bool "Cirrus Logic Madera codecs with SPI"
> > > > > > +       select MFD_MADERA
> > > > > > +       select REGMAP_SPI
> > > > > > +       depends on SPI_MASTER
> > > > > > +       depends on PINCTRL
> > > > > > +       help
> > > > > > +         Support for the Cirrus Logic Madera platform audio SoC
> > > > > > +         core functionality controlled via SPI.
> > > > >
> > > > >
> > > > >
> > > > > Why do the I2C and SPI subdrivers depend on PINCTRL?
> > > > >
> > > > > They sure don't seem to be using any pinctrl-specific APIs.
> > > >
> > > > They require PINCTRL even if they don't call any functions on it because
> > > > the
> > > > chip won't work correctly if there isn't a PINCTRL driver to apply the
> > > > correct pinmux configuration.
> > >
> > >
> > > Apply the configuration to what? Sorry I don't get it.
> > >
> > > You can't be referring to the internal pin controller of the Madera, since
> >
> > Yes I am
>
> You are saying that the I2C and SPI interface to the Madera codec
> depends on pin control.
>
> It does not.
>
> You can most certainly talk I2C and SPI to the coded without any
> pin control. Probably the MFD driver can come up without it.
>
> If what you want is unconditional pin control enabled for this circuit,
> then have MFD_MADERA select PINCTRL.
>
> > > that has to come up before its pin controller can even be communicated
> > > with.
> >
> >
> > So?
> >
> > The MFD driver powers up the chip before registering child drivers.
>
> Including the pin controller. You just confirmed what I said: the
> I2C and SPI interfaces do not require pin control to talk to the
> chip.
>
> > Also that's not entirely relevant, the pinctrl settings can still be written
> > with the chip off because they will go into the regmap cache and be applied
> > when the chip is next resumed.
>
> You still have the dependencies wrong.
>
> Yours,
> Linus Walleij

So the short version of this email thread is that it should be "select 
PINCTRL" ?