Re: [PATCH 4/7] soc/tegra: pmc: Add interface to set voltage of IO rails

[Stephen Warren]

On 04/15/2016 10:33 AM, Laxman Dewangan wrote:
> On Friday 15 April 2016 10:11 PM, Stephen Warren wrote:
> > On 04/15/2016 10:21 AM, Laxman Dewangan wrote:
> > > On Friday 15 April 2016 09:54 PM, Stephen Warren wrote:
> > > > On 04/12/2016 08:56 AM, Laxman Dewangan wrote:
> > > > > NVIDIA Tegra210 supports some of the IO interface which can operate
> > > > > at 1.8V or 3.3V I/O rail voltage levels. SW needs to configure
> > > > > Tegra PMC register to set different voltage level of IO interface
> > > > > based
> > > > > on IO rail voltage from power supply i.e. power regulators.
> > > > >
> > > > > Add APIs to set and get IO rail voltage from the client driver.
> > > >
> > > > > diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
> > > >
> > > > > +static struct tegra_io_rail_voltage_bit_info
> > > > > tegra210_io_rail_voltage_info[] = {
> > > > > +    TEGRA_IO_RAIL_VOLTAGE(SDMMC1, 12),
> > > > > +    TEGRA_IO_RAIL_VOLTAGE(SDMMC3, 13),
> > > > > +    TEGRA_IO_RAIL_VOLTAGE(AUDIO_HV, 18),
> > > > > +    TEGRA_IO_RAIL_VOLTAGE(DMIC, 20),
> > > > > +    TEGRA_IO_RAIL_VOLTAGE(GPIO, 21),
> > > > > +    TEGRA_IO_RAIL_VOLTAGE(SPI_HV, 23),
> > > > > +};
> > > >
> > > > That table is likely specific to Tegra210, yet ...
> > > >
> > > > > +static int tegra_io_rail_voltage_get_bit_pos(int io_rail_id)
> > > > > +int tegra_io_rail_voltage_set(int io_rail, int val)
> > > > > +int tegra_io_rail_voltage_get(int io_rail)
> > > >
> > > > ... these functions are all named as if they are generic. Presumably
> > > > they will indeed be needed for the next chip too? How will you prevent
> > > > their use, or turn these functions into no-ops, or return errors, on
> > > > other SoCs?
> > >
> > > It will return error for the Soc which does to support or the parameter
> > > to the apis which are not applicable.
> >
> > Are you saying that will happen in the current code? I don't see where
> > there's anything that validates that.
> >
> > Or does "will" mean "I will do that in the next patch revision"?
>
> I have code like this in this patch
>
>
> +int tegra_pmc_pad_voltage_update(unsigned long offset, unsigned long mask,
> +                                unsigned long val)
> +{
> +       unsigned long flags;
> +
> +       if (!pmc->soc->has_pad_voltage_config)
> +               return -ENODEV;
> +
>
>
> So this flag is try only for T210 and all previous chip has false setting.

I assume that's in the next patch revision? I don't see it in the 
patches you posted.