Re: [RFC] ACPI: Add GPIO-signaled event simulator.

[Tomasz Nowicki]

On 08.08.2014 14:36, Linus Walleij wrote:
> On Thu, Jul 24, 2014 at 5:51 PM, Tomasz Nowicki
> <tomasz.nowicki@xxxxxxxxxx> wrote:
>
> > GPIO signaled events is quite new thing in Linux kernel.
> > AFAIK, there are not many board which can take advantage of it.
> > However, GPIO events are very useful feature during work on ACPI
> > subsystems.
>
> Overall this seems like a pretty nice debug feature.
>
> > This commit emulates GPIO h/w behaviour and consists on read/write
> > operation to debugfs file. GPIO device instance is still required in DSDT
> > table along with _AEI resources and event methods.
> >
> > Reading from file provides pin to GPIO device map e.g. :
> > $ cat /sys/kernel/debug/acpi/gpio_event
> > GPIO device name: /__SB.GPI0
> > Available GPIO pin map:
> > /__SB.GPI0 <-> pin 0x100
> >
> > Based on that, user can trigger method corresponding to device pin number:
> > $ echo "/__SB.GPI0 0x100" > /sys/kernel/debug/acpi/gpio_event
>
> I need input from Rafael and Mika as to whether this is a
> good interface.
>
> It seems a bit confusing for me: why do you have to extract
> a number from one file and then insert the same magic number
> somewhere else?

Good point! Available GPIO event pins should be listed as debugfs node, 
then user would write e.g. 1 to one particular. Sounds simpler.

Regards,
Tomasz Nowicki
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