On 13/06/16 12:59, Marc Zyngier wrote: > On 13/06/16 12:09, Jon Hunter wrote: >> >> On 13/06/16 11:42, Marc Zyngier wrote: >>> On 07/06/16 16:12, Jon Hunter wrote: >>>> For some devices the IRQ trigger type for a device is read from >>>> firmware, such as device-tree. The IRQ trigger type is typically read >>>> when the mapping for IRQ is created, which is before the IRQ is >>>> requested. Hence, the IRQ trigger type is programmed when mapping the >>>> IRQ and not when requesting the IRQ. >>>> >>>> Although this works for most cases, in order to support IRQ chips which >>>> require runtime power management, which may not be accessible prior >>>> to requesting the IRQ, it is desirable to look-up the IRQ trigger type >>>> when it is requested. Therefore, if the IRQ trigger type is not >>>> specified when __setup_irq() is called, look-up the saved IRQ trigger >>>> type. This will allow us to defer the programming of the trigger type >>>> from when the IRQ is mapped to when it is actually requested. >>>> >>>> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx> >>>> Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx> >>>> --- >>>> kernel/irq/manage.c | 7 +++++++ >>>> 1 file changed, 7 insertions(+) >>>> >>>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c >>>> index ef0bc02c3a70..eaedeb74b49d 100644 >>>> --- a/kernel/irq/manage.c >>>> +++ b/kernel/irq/manage.c >>>> @@ -1117,6 +1117,13 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) >>>> new->irq = irq; >>>> >>>> /* >>>> + * If the trigger type is not specified by the caller, >>>> + * then use the default for this interrupt. >>>> + */ >>>> + if (!(new->flags & IRQF_TRIGGER_MASK)) >>>> + new->flags |= irqd_get_trigger_type(&desc->irq_data); >>>> + >>>> + /* >>>> * Check whether the interrupt nests into another interrupt >>>> * thread. >>>> */ >>>> >>> >>> I've added the following patch to the queue, in order to deal with >>> percpu interrupts that were not handled by this patch: >>> >>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c >>> index f8fd1fb..00cfc85 100644 >>> --- a/kernel/irq/manage.c >>> +++ b/kernel/irq/manage.c >>> @@ -1751,7 +1751,14 @@ void enable_percpu_irq(unsigned int irq, unsigned int type) >>> if (!desc) >>> return; >>> >>> + /* >>> + * If the trigger type is not specified by the caller, then >>> + * use the default for this interrupt. >>> + */ >>> type &= IRQ_TYPE_SENSE_MASK; >>> + if (type == IRQ_TYPE_NONE) >>> + type = irqd_get_trigger_type(&desc->irq_data); >>> + >> >> I am wondering if you need this here because now __setup_irq(), called >> by request_percpu_irq(), will actually look-up the saved type even for a >> percpu-irq. So shouldn't this already be handled? Or am I missing something? > > You are overlooking the fact that the configuration registers are > themselves per-CPU, which means that __setup_irq() will only configure > the interrupt on the CPU it runs on. And you can't even tell which one, > since you are in a preemptible context. > > Does it make more sense? Yes it does thanks. I am guessing we don't need to worry about there being different type configurations for the different CPUs for a given interrupt? Cheers Jon -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
