On Thu, Jan 23, 2014 at 11:38:06PM +0100, Sebastian Hesselbarth wrote: > Bridge IRQ_CAUSE bits are asserted regardless of the corresponding bit in > IRQ_MASK register. To avoid interrupt events on stale irqs, we have to clear > them before unmask. This installs an .irq_enable callback to ensure stale > irqs are cleared before initial unmask.
I'm not sure if putting this in irq_enable is correct. I think this should only happen at irq_startup. The question boils down to what is supposed to happen with this code sequence: disable_irq(..); write(.. something to cause an interrupt edge ..); .. synchronize .. enable_irq(..); Do we get the interrupt or not? I found this message from Linus long ago: http://yarchive.net/comp/linux/edge_triggered_interrupts.html > Btw, the "disable_irq()/enable_irq()" subsystem has been written so that > when you disable an edge-triggered interrupt, and the edge happens while > the interrupt is disabled, we will re-play the interrupt at enable time. > Exactly so that drivers can have an easier time and don't have to > normally worry about whether something is edge or level-triggered. And found this note in Documentation/DocBook/genericirq.tmpl: > This prevents losing edge interrupts on hardware which does > not store an edge interrupt event while the interrupt is disabled at > the hardware level. So I think it is very clear that the chip driver should not discard edges that happened while the interrupt was disabled. Regards, Jason -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
