Messages in this thread | | | Date | Mon, 30 Nov 2009 22:15:38 +0200 | Subject | Re: Get rid of IRQF_DISABLED - (was [PATCH] genirq: warn about IRQF_SHARED|IRQF_DISABLED) | From | Andrew Victor <> |
| |
hi,
> There is hardware out there (AT91) where > the timer interrupt is shared with other peripherals, and you end > up with a mixture of irqs-disabled and irqs-enabled handlers sharing > the same interrupt.
For the AT91 case I don't think this shouldn't matter.
The AT91's have a priority-level interrupt controller, so: 1. a lower-priority interrupt won't interrupt a higher-priority 2. shared interrupts cannot interrupt each other until irq_finish() is called (a write to AIC_EOICR)
Since the Timer, DBGU serial port (and other system peripherals) are on the same priority level they cannot interrupt each other. (ie, basically as-if always irqs-disabled).
The case of irqs-enabled does means that a higher-priority interrupt could interrupt [*], but it's not a shared-IRQ in that case.
([*] The system peripherals have the highest priority by default, so the user would need to override the defaults for this to occur)
Regards, Andrew Victor
| |