Messages in this thread | | | Date | Tue, 3 Feb 2009 09:59:34 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: Reworking suspend-resume sequence (was: Re: PCI PM: Restore standard config registers of all devices early) |
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On Tue, 3 Feb 2009, Rafael J. Wysocki wrote: > > Having reconsidered it, I think that the "loop of disable_irq()" may be > problematic due to MSI/MSI-X and devices that are put into D3 during the > "normal" suspend. That is, we shouldn't try to mask MSI/MSI-X for devices in > D3
Rafael, you seem to be confused about what "disable_irq()" does.
It does not touch the driver hardware AT ALL. It literally just touches the interrupt controller, and even that only indirectly.
What disable_irq() does it literally:
void disable_irq_nosync(unsigned int irq) { struct irq_desc *desc = irq_to_desc(irq); unsigned long flags; if (!desc) return;
spin_lock_irqsave(&desc->lock, flags); if (!desc->depth++) { desc->status |= IRQ_DISABLED; desc->chip->disable(irq); } spin_unlock_irqrestore(&desc->lock, flags); }
and then it does a "synchronize_irq()" to wait to make sure that there are no pending ones.
And in many cases, even the
desc->chip->disable(irq);
doesn't actually _do_ anything - we'll quite possibly continue to take the interrupt, and only when the interrupt happens will it see the "oh, IRQ_DISABLED is set" thing, and do something about it.
So don't worry about putting devices in D3 - disable_irq() will not care AT ALL whether the device is alive or not, and will never try to touch it anyway.
Linus
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