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    SubjectRe: [PATCH] PM: suspend_device_irqs(): don't disable wakeup IRQs
    On Sat, May 30, 2009 at 8:35 AM, Rafael J. Wysocki <> wrote:
    > On Monday 25 May 2009, Kim Kyuwon wrote:
    >> Rafael J. Wysocki wrote:
    >> > On Saturday 23 May 2009, Kim Kyuwon wrote:
    >> >> On Sat, May 23, 2009 at 7:29 AM, Rafael J. Wysocki <> wrote:
    >> >>> On Saturday 23 May 2009, Kim Kyuwon wrote:
    >> > [--snip--]
    >> >>>> You changed the really important part of Linux, which may affect most
    >> >>>> processor architectures. I think you should be careful. If some of
    >> >>>> architectures can't take care of it (they can implement
    >> >>>> disable_irq_wake correctly in H/W level, will you revert your changes?
    >> >>> No, the changes are not going to be reverted.  In fact things should have been
    >> >>> done like this already much earlier.
    >> >>>
    >> >>> Now, do you have any particular example of a problem related to these changes
    >> >>> or is it only a theoretical issue?
    >> >> I'd CCing you when I'm sending a mail for this particular example of a example.
    >> >>
    >> >
    >> > Well, as I said above, reverting the changes that introduced
    >> > [suspend|resume]_device_irqs() is not an option, becuase it was the only sane
    >> > way to achieve the goal they were added for.  So, we need to fix the wake-up
    >> > problem on your platform with the assumption that
    >> > [suspend|resume]_device_irqs() are going to stay.
    >> >
    >> > For starters, would it be possible to teach the 'disable' hook of your
    >> > platform's interrupt controller not to mask the IRQs that have both
    >> > IRQ_WAKEUP and IRQ_SUSPENDED set?  That apparently would work around the
    >> > wake-up interrupts problem.
    >> Thank you for considering this issue and spending your time. In order to
    >> make your idea work, we need to add a dummy 'set_wake' hook which
    >> returns always zero. Anyway, IMO, I think your idea is good to work
    >> around this problem. But Kevin Hilman(OMAP PM Maintainer) would make
    >> final decision.
    >> Buy the way, how can you handle the problem that a few interrupt are
    >> discarded in a small window? I can be sure they are discarded, because I
    >> have debugged defects which generate in sleep/resume state hundreds of
    >> times on ARM Processors(PXA310, S3C6410, OMAP3430). Wake-up interrupts
    >> are generated as soon as arch_suspend_enable_irqs() invoked.
    > Sorry for the delayed response.
    > If the wake-up interrupts are not masked, they will be delivered to the drivers
    > as soon as arch_suspend_enable_irqs() has run.  So, if the drivers are able to
    > handle them at this point (ie. before resume_device_irqs() is called), they
    > won't be lost.

    Thank you for your response!

    Your suspend_device_irqs() disables all IRQs(except timer IRQ) while
    entering suspend. i.e. Before invoking resume_device_irqs() or
    resume_noirq callback, all IRQs(except timer IRQ) is in IRQ_DISABLED
    status. Right?
    But if an IRQ is in IRQ_DISABLED status, its interrupt handler can be
    invoked. (As you know, all IRQs with IRQ_DISABLE are not handled in
    handle_level_irq function). Thus, even if the wake-up interrupts are
    not masked, the drivers are not able to handle interrupts, because the
    interrupt handler can't be invoked due to IRQ_DISABLED set by

    > The only problem I see is that the drivers may expect their
    > ->resume_noirq() callbacks to be executed first.

    resume_noirq() callbacks are also invoked after arch_suspend_enable_irqs().

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      Last update: 2009-05-30 09:37    [W:0.029 / U:6.348 seconds]
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