Re: [PATCH] gpio: zynq: Implement irq_(request|release)_resources

[Grygorii Strashko]

On 10/27/2015 05:53 PM, Linus Walleij wrote:
> On Fri, Oct 23, 2015 at 3:36 PM, Soren Brinkmann
> <soren.brinkmann@xxxxxxxxxx> wrote:
>
> > The driver uses runtime PM to leverage low power techniques. For
> > use-cases using GPIO as interrupt the device needs to be in an
> > appropriate state.
> >
> > Reported-by: John Linn <linnj@xxxxxxxxxx>
> > Signed-off-by: Soren Brinkmann <soren.brinkmann@xxxxxxxxxx>
> > Tested-by: John Linn <linnj@xxxxxxxxxx>
>
> As pointed out by Grygorii in
> commit aca82d1cbb49af34b69ecd4571a0fe48ad9247c1:
>
>      The PM runtime API can't be used in atomic contex on -RT even if
>      it's configured as irqsafe. As result, below error report can
>      be seen when PM runtime API called from IRQ chip's callbacks
>      irq_startup/irq_shutdown/irq_set_type, because they are
>      protected by RAW spinlock:
> (...)
>      The IRQ chip interface defines only two callbacks which are executed in
>      non-atomic contex - irq_bus_lock/irq_bus_sync_unlock, so lets move
>      PM runtime calls there.
>
> I.e. these calls are atomic context and it's just luck that it works
> and this is fragile.
>
> Can you please check if you can move it to
> irq_bus_lock()/irq_sync_unlock()
> like Grygorii does?

This patch rises the question not only about PM runtime, but also
about gpiochip_irq_reqres()/gpiochip_irq_relres().


--
regards,
-grygorii
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/