[U-Boot] [linux-sunxi] Re: [PATCH 6/9] ARM: sunxi: Add support for R_PIO gpio banks

[Chen-Yu Tsai]

Hi Ian,

On Mon, Oct 13, 2014 at 8:57 PM, Maxime Ripard
<maxime.ripard at free-electrons.com> wrote:
> On Sun, Oct 12, 2014 at 04:23:05PM +0800, Chen-Yu Tsai wrote:
>> On Sun, Oct 12, 2014 at 12:05 AM, Ian Campbell <ijc at hellion.org.uk> wrote:
>> > On Tue, 2014-10-07 at 15:11 +0800, Chen-Yu Tsai wrote:
>> >> From: Hans de Goede <hdegoede at redhat.com>
>> >>
>> >> The A31, A23 and later SoCs have an extra pin controller, called CPUs_PIO
>> >> or R_PIO, which handles pin banks L and beyond.
>> >
>> > Does it also have enough space for 9 banks? Since you overlay a struct
>> > sunxi_gpio_reg on it which has a gpio_bank[SUNXI_GPIO_BANKS] over it.
>>
>> Yes it does, as seen in the latest A31 manuals released by Allwinner.
>>
>> > SUNXI_GPIO_BANKS is now also confusingly named since it is really
>> > "number of banks on the first/original GPIO controller". Eventually
>> > someone will use it as the actual total and be very sad.
>> >
>> > I think it might be best if we retcon some distinct name onto the
>> > original GPIO controller so we can have SUNXIO_GPIO_BLA_BANKS and
>> > SUNXI_GPIO_R_BANKS (or even just call them controller 0 and 1 and have
>> > SUNXI_GPIO0_BANKS and SUNXI_GPIO1_BANKS, if that's not too confusing)
>>
>> The latest manuals have "CPUx-PORT" and "CPUs-PORT" for the respective
>> chapters. I'm guessing "x" is for 0~3 cores, and s is for standby or
>> something.
>
> iirc, it was meant for "special".

I'd like to keep it as SUNXI_GPIO_BANKS if possible. The GPIO and R_GPIO
prefixes match what we see in Allwinner's sources and what we use in the
mainline kernel.

The comment section above it could be made clearer about it.

Also that number would be bumped up for A80, which has pin bank J.
I will change some of the R_PIO code to check/use the starting pin bank L
number instead of checking against SUNXI_GPIO_BANKS. Wonder why I didn't
do it before...

>> Of course it's also confusing that Allwinner's sources use the "R_"
>> prefix for all hardware in that address range, while the datasheet
>> lists the GPIO function names as "s_something".
>
> We use the same pin convention than in the datasheet in mainline (but
> starting from PL for the special pins). And it's true that we do
> prefix all the functions by s_, once again, just like the datasheet
> does.
>
> The fact that it comes from a different controller is only expressed
> by where the pinctrl pins node is defined in the DT.

I'm a bit undecided about how we should name the pin definitions.
In the kernel, we named the function s_uart, but the pinconf node
r_uart.

In u-boot there isn't this separation. I'm wondering which would be
easier to understand and relate to the underlying peripheral.
At the moment I prefer R_UART.


ChenYu