On Wednesday 22 October 2014 11:10:44 Mika Westerberg wrote:
>
> It expects that GPIOs returned from _CRS are in specific order. Since we
> can't change these existing ACPI tables, we must support them somehow.
>
> This patch series handles it so that:
>
> 1) If we can't find given property (e.g "reset-gpios" or
> "shutdown-gpios") the index above will refer directly to the GPIO
> resource returned from _CRS.
>
> 2) If the property is found we ignore index and take it from the
> property instead.
>
> This has the drawback that we cannot support this:
>
> Package () { "reset-gpios", Package () { ^GPIO, 0, 0, 0, ^GPIO, 1, 0, 0}}
> ^^^^^^^^^^^^^^
> So the second entry in the above is not accessible using
> gpiod_get_index() and the reason is that we want to support the existing
> and new ACPI tables where _DSD is not being used.
So this is not using the DT binding but does thing slightly differently then.
In this case (supporting two incompatible bindings for DT and ACPI), I think
the only sensible driver implementation would be to know what we are asking
for and use different devm_gpiod_get_index statements based on the firmware
interface.
Arnd
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