Re: [PATCH 0/4] gpio: pxa: integrate with pincontrol

[Robert Jarzmik <robert.jarzmik@xxxxxxx>]

Linus Walleij <linus.walleij@xxxxxxxxxx> writes:

> On Sat, Nov 28, 2015 at 10:37 PM, Robert Jarzmik <robert.jarzmik@xxxxxxx> wrote:
>
>> Hi Linus, Alexandre and Haojian,
>>
>> This serie aims at several cleanups and improvements in the pxa gpio driver, to
>
> I have concerns about this series.
>
> I am worried that joining the banks into one gpio_chip makes it
> impossible for you GPIOLIB_IRQCHIP. Usually that is possible and
> preferrable when using a chained handler if e.g. one bank has
> one IRQ line.
>
> But overall that depends on how the IRQs map on this hardware.
> Can you describe how the GPIO IRQs work on the PXA27x?
Of course.

For PXA27x, there are 3 interrupts directly connected to the CPU of the SoC,
ie. the primary irq controller :
 - one is only triggered if GPIO0 has a rising/falling edge
 - one is only triggered if GPIO1 has a rising/falling edge
 - the last is triggered if any GPIOn has a rising/falling edge (n >= 2)

The condition to program the rising/falling edge which implies the interrupt to
be asserted is in a GPIO block register, GFER and GRER (1 bit per GPIO).

The fact that the last interrupt (let's call it gpiomux_irq) is triggered by
GPIOs from _all_ the banks makes me believe it's a single IP block, ie. a single
chip.

Now if you have concerns with this, then maybe you can advise another approach,
I'm pretty open. The final goal will be for me :
 - gpio and pinctrl have to cooperate
   - today, with the current state, it's impossible to map pins 0..127 to gpios
     0..127, at least in a device-tree .dts file
   - the GPDR (gpio direction register) shared access bothers me a bit

Cheers.

-- 
Robert
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