On Mon, 19 Sep 2016, Marc Zyngier wrote:
> There is no point in trying to configure the trigger of a chained
> interrupt if no trigger information has been configured. At best
> this is ignored, and at the worse this confuses the underlying
> irqchip (which is likely not to handle such a thing), and
> unnecessarily alarms the user.
> 
> Only apply the configuration if type is not IRQ_TYPE_NONE.
> 
> Reported-by: Geert Uytterhoeven <ge...@linux-m68k.org>
> Fixes: 1e12c4a9393b ("genirq: Correctly configure the trigger on chained 
> interrupts")
> Link: 
> https://lkml.kernel.org/r/CAMuHMdVW1eTn20=etycj8hkvwohasuh_yqxry2mgbevz8fp...@mail.gmail.com
> Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
> ---
>  kernel/irq/chip.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> index 6373890..26ba565 100644
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -820,6 +820,8 @@ __irq_do_set_handler(struct irq_desc *desc, 
> irq_flow_handler_t handle,
>       desc->name = name;
>  
>       if (handle != handle_bad_irq && is_chained) {
> +             unsigned int type = irqd_get_trigger_type(&desc->irq_data);
> +
>               /*
>                * We're about to start this interrupt immediately,
>                * hence the need to set the trigger configuration.
> @@ -828,8 +830,10 @@ __irq_do_set_handler(struct irq_desc *desc, 
> irq_flow_handler_t handle,
>                * chained interrupt. Reset it immediately because we
>                * do know better.
>                */
> -             __irq_set_trigger(desc, irqd_get_trigger_type(&desc->irq_data));
> -             desc->handle_irq = handle;
> +             if (type != IRQ_TYPE_NONE) {
> +                     __irq_set_trigger(desc, type);
> +                     desc->handle_irq = handle;

Are you really sure that the handler should only be set when the trigger
type is != NONE? I seriously doubt that this is correct.

Thanks,

        tglx


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