[PATCH v2] gpio: Add Avionic Design N-bit GPIO expander support

[Linus Walleij]

On Mon, Aug 6, 2012 at 7:11 AM, Thierry Reding
<thierry.reding at avionic-design.de> wrote:
> On Sun, Aug 05, 2012 at 12:50:54PM +0200, Linus Walleij wrote:

>> We're working on a goal of a "single zImage" (one unified ARM
>> kernel) which means your platform must be able to handle the
>> case where this is turned on anyway, so I would suggest you
>> drop the optional compile-time IRQ support, just make it
>> optional at runtime instead.
>
> I don't quite understand. Do you want me to add a module parameter to
> make it optional at runtime? Since the driver is now OF only I suppose I
> could make it optional on the interrupt-controller property as well.

No, no module parameter. Just don't register the IRQ domain if there
are not IRQ resources in the device tree, if the interrupt-controller
property is not present I guess?

>> OK but atleast find a way to move this to the probe() function,
>> what happens if the debugfs file is browsed and you run out
>> of memory? Not nice, and you were using this to debug as
>> well...
>
> Alright, I can do that. Alternatively I could probably drop the
> allocations altogether and use local variables within the second loop to
> store the variables:
>
>         for (i = 0; i < num_regs; i++) {
>                 u8 ddr, plr, ier, isr, ptr;
>
>                 err = adnp_read(gpio, GPIO_DDR(gpio) + i, &ddr);
>                 if (err < 0)
>                         goto out;
>
>                 ...
>         }
>
> With the proper locking this shouldn't be a problem. The reason why I
> used the block-wise approach in the first place was that the register
> accesses were more "atomic". Of course without locking this is non-
> sense.

Either approach works, the above seems more elegant though!

Yours,
Linus Walleij