Re: [PATCH V9] virtio-gpio: Add support for interrupts

[Viresh Kumar <viresh.kumar@linaro.org>]

On 12-10-21, 11:16, Arnd Bergmann wrote:
> I don't see a problem with the flexibility, but I find the inconsistency
> slightly annoying: if disabling the interrupt line has the side-effect of
> masking it, it should not be possible to unmask it before enabling.

I agree, this doesn't look consistent here.

> To have it more consistent, it would seem better to do one of two
> things:
> 
> a) require disabled interrupts to always be masked, only allowing
>     the unmask to happen after enable, while forcing a mask
>     during disable.
> 
> or
> 
> b) separate the 'mask' from the 'disable' operation, leaving the
>     event descriptor queued if you disable it, but adding another
>     operation for an explicit mask (i.e. return the event descriptor)
>     that is separate from 'disable'.
> 
> I would prefer a) here since I think that makes a nicer virtio spec,
> but b) would make it more similar to hardware gpio controllers.
> 
> In the end, I don't think any of the combinations would cause
> problems, this is just a matter of personal taste.

I also like option A to be a better (easier) choice here, though it
may make the Linux implementation a bit inefficient (maybe few extra
if/else blocks while enabling/disabling irqs). I will update this in
the next version then.

-- 
viresh