On Saturday 20 October 2007 04:25:34 Linus Torvalds wrote:
>
> On Sat, 20 Oct 2007, Maxim Levitsky wrote:
> >
> > and the interrupt handler:
> >
> > smp_rmb();
> > if (dev->insuspend)
> > goto out;
>
> Something like that can work, yes. However, you need to make sure that:
>
> - even when you ignore the interrupt (because the driver doesn't care,
> it's suspending), you need to make sure the hardware gets shut up by
> reading (or writing) the proper interrupt status register.
I agree, but while device is powered off, its registers can't be accessed
Thus, if I ack the IRQ every time the handler is called, I will access the
powered off device (this is probably won't hurt a lot, but a bit incorrectly)
>
> Otherwise, with a level interrupt, the interrupt will continue to be
> held active ("screaming") and the CPU will get interrupted over and
> over again, until the irq subsystem will just turn the irq off
> entirely.
>
> - when you resume, make sure that you get the engine going again, with
> the understanding that some interrupts may have gotten ignored.
Here it isn't a problem, this is a video capture card, and I suspend it by just stopping dma
on all active buffers even if in the middle of capture, and I send those buffers to card again
to fill them from the beginning during the resume.
>
> Also, in general, these kinds of things shouldn't always even be
> neicessary. If you use the suspend_late()/resume_early() hooks, those will
> be called with interrupts off, and while they can be harder to debug (and
> may be worth avoiding for non-critical drivers), they do allow for simpler
> models partly exactly because they don't need to worry about interrupts
> etc.
Exactly, I am aware of suspend_late , but I don't want to abuse it.
>
> Linus
>
Best regards,
Maxim Levitsky
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