[PATCH 1/2] pinctrl: Add support for Meson8b

[Carlo Caione]

On Sun, Mar 8, 2015 at 9:46 AM, Beniamino Galvani <b.galvani at gmail.com> wrote:
> On Fri, Mar 06, 2015 at 04:51:15PM +0100, Carlo Caione wrote:
>> From: Carlo Caione <carlo at endlessm.com>
>>
>> This patch adds pinctrl support for the AmLogic Meson8b SoC.
>
> Hi Carlo,

Hi Beniamino,

>> [...]
>> +static const unsigned int xtal_24m_pins[]    = { PIN_GPIOY_3 };
>> +static const unsigned int iso7816_2_clk_pins[]       = { PIN_GPIOY_13 };
>> +static const unsigned int iso7816_2_data_pins[] = { PIN_GPIOY_14 };
>> +
>> +
>
> Just a nitpick, there is a double empty line here.

Nitpicks are welcome.

>> [...]
>> +static const unsigned int remote_input_pins[]        = { PIN_GPIOAO_7 };
>> +static const unsigned int hdmi_cec_1_pins[]  = { PIN_GPIOAO_12 };
>> +static const unsigned int ir_blaster_pins[]  = { PIN_GPIOAO_13 };
>> +
>> +
>
> The same here.

Ok

>> [...]
>> +/* First GPIO chip */
>> +#define GPIOX_0              0
>> +#define GPIOX_1              1
>> +#define GPIOX_2              2
>> +#define GPIOX_3              3
>> +#define GPIOX_4              4
>> +#define GPIOX_5              5
>> +#define GPIOX_6              6
>> +#define GPIOX_7              7
>> +#define GPIOX_8              8
>> +#define GPIOX_9              9
>> +#define GPIOX_10     10
>> +#define GPIOX_11     11
>> +#define GPIOX_16     12
>
> This kind of pin numbering breaks the selection of the bit for a given
> pin in meson_calc_reg_and_bit(). Looking at the documentation it seems
> that pins GPIOX_12 through 15 are not available but their bit exist in
> the register and we must take that into account.
>
> For example GPIOX_10 and GPIOX_11 are associated to bits 10 and 11 of
> register 1 for changing the direction and GPIOX_16 to bit 16; but with
> the above assignment the function would select bit 12 for GPIOX_16.

Right. Fix coming in v2.
Probably the most sensible thing to do is to reuse the same
meson8-gpio.h integrated with the DIF bank pins missing from meson8
and only present in Meson8b.

> The strange thing is that the pins that are missing in the
> documentation (as GPIOX12-15, GPIOY_2 and others) not only are defined
> but also have some associated mux configuration in Amlogic kernel
> sources.

Looking at the pin-out diagram I have for the Meson8b it seems that
those GPIOs are missing from the SoC pin-out, so I think that the
documentation is more correct in this sense.

> I'm not very familiar with the inner mechanisms of the pinctrl
> subsystem, but I guess that holes in the numbering of pins wouldn't be
> a problem and thus we can skip the numbers associated to non-existent
> pins (i.e. GPIOX_11 -> 11, GPIOX_16 -> 16). Pinctrl experts please
> correct me if I'm wrong :)

Linus, any thought on that?
The only problem I see is that since the BANK macro works with 'first'
and 'last' without considering holes, we will be mapping GPIOs that do
not actually exist in our SoC.

> Or we could just pretend that the missing pins exist even if the
> documentation says otherwise.

I totally agree.

Thanks,

-- 
Carlo Caione