On 25/10/2016 12:45, Marc Zyngier wrote: > On 25/10/16 09:36, Mason wrote: >> On 25/10/2016 10:29, Sebastian Frias wrote: >> >>> On 10/24/2016 06:55 PM, Thomas Gleixner wrote: >>> >>>> On Mon, 24 Oct 2016, Mason wrote: >>>> >>>>> For the record, setting the IRQ_DISABLE_UNLAZY flag for this device >>>>> makes the system lock-up disappear. >>>> >>>> The way how lazy irq disabling works is: >>>> >>>> 1) Interrupt is marked disabled in software, but the hardware is not masked >>>> >>>> 2) If the interrupt fires befor the interrupt is reenabled, then it's >>>> masked at the hardware level in the low level interrupt flow handler. >>> >>> Would you mind explaining what is the intention behind? >>> Because it does not seem obvious why there isn't a direct map between >>> "disable_irq*()" and "mask_irq()" >> >> I had a similar, but slightly different question: >> >> What is the difference between struct irq_chip's >> >> * @irq_shutdown: shut down the interrupt (defaults to ->disable if NULL) >> * @irq_disable: disable the interrupt >> * @irq_mask: mask an interrupt source > > One important difference between disable and mask is that disable is > perfectly allowed not to care about pending signals, whereas mask must > preserve an interrupt becoming pending whilst masked.
(For my information) Is it correct to say that "mask" is supposed to defer any interrupt until sometime later; while "disable" will simply discard incoming interrupts, losing them forever. Is the irq_mask() call-back exposed via some module-visible API? include/linux/interrupt.h documents mostly enable/disable variants. extern void disable_irq_nosync(unsigned int irq); extern bool disable_hardirq(unsigned int irq); extern void disable_irq(unsigned int irq); extern void disable_percpu_irq(unsigned int irq); extern void enable_irq(unsigned int irq); extern void enable_percpu_irq(unsigned int irq, unsigned int type); extern bool irq_percpu_is_enabled(unsigned int irq); extern void irq_wake_thread(unsigned int irq, void *dev_id); Regards.
