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

[Laxman Dewangan]

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.