Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> writes:
> Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> writes:
>
>> "Rafael J. Wysocki" <rjw@xxxxxxx> writes:
>>
>>> On Wednesday 06 May 2009, Kevin Hilman wrote:
>>>> Arve Hjønnevåg <arve@xxxxxxxxxxx> writes:
>>>>
>>>> > On Tue, May 5, 2009 at 8:52 AM, Kevin Hilman
>>>> > <khilman@xxxxxxxxxxxxxxxxxxx> wrote:
>>>> >> Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> writes:
>>>> >>
>>>> >>> On Mon, 4 May 2009 17:27:04 -0700 Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> wrote:
>>>> >>>
>>>> >>>> Interrupts that are flagged as wakeup sources via set_irq_wake()
>>>> >>>> should not be disabled for suspend.
>>>> >>>>
>>>> >>>
>>>> >>> Why not?
>>>> >>>
>>>> >>
>>>> >> If an interrupt is a wakeup source, and it is disabled at the chip
>>>> >> level, it will no longer generate interrupts, and thus no longer wake
>>>> >> up the system.
>>>> >>
>>>> >> I'd be interested in hearing why wakeup interrupts should be disabled
>>>> >> during suspend.
>>>
>>> That depends on whether or not they are used for anything else than wake-up.
>>>
>>>>
>>>> [...]
>>>>
>>>> >>>
>>>> >>> If this fixes some bug then please provide a description of that bug?
>>>> >>
>>>> >> The bug is that on TI OMAP, interrupts that are used for wakeup events
>>>> >> are disabled by this code causing the system to no longer wake up.
>>>> >
>>>> > What do you do if the interrupt triggers right after your driver has
>>>> > returned from its late suspend hook?
>>>>
>>>> If it's a wakeup IRQ, I assume you want it to prevent suspend.
>>>>
>>>> But I don't see how that can happen in the current code. IIUC, by the
>>>> time your late suspend hook is run, your device IRQ is already
>>>> disabled, so it won't trigger an interrupt that will be caught by
>>>> check_wakeup_irqs() anyways.
>>>
>>> My understanding of __disable_irq() was that it didn't actually disable the
>>> IRQ at the hardware level, allowing the CPU to actually receive the interrupt
>>> and acknowledge it, but preventing the device driver for receiving it.
>>
>> Hmm, that's not normally what I think of as disabled. ;)
>>
>>> Does it work differently on the affected systems?
>>
>> Yes.
>>
>> __disable_irq() calls the irq_chip's disable method which is platform
>> specific. On OMAP, this masks the IRQ at the hardware level
>> preventing the CPU from seeing the interrupt.
>
> So just as a test, I just removed the 'disable' hook from my platforms
> irq_chip and this allows me to wakeup without using my proposed patch,
> although I'm not sure it is the right behavior either.
>
> The 'struct irq_chip' comments are a bit misleading here as it says
>
> * @disable: disable the interrupt (defaults to chip->mask if NULL)
>
> And since my irq_chip->disable was doing basically the same thing as
> my irq_chip->mask, I didn't expect it to change behavior. But in
> kernel/irq/chip.c, disable gets set to an empty default_disable if the
> irq_chip's version is NULL.
>
> The result is that if irq_chip->disable == NULL, suspend_device_irqs() is a
> big NOP, albiet one that does lots of locking. :)
>
> So, should the irq_chip code be fixed to match the comment? Something
> like the patch below? If I fix the IRQ chip code, then I'm back to
> needing my patch since my irq_chip mask function still masks the IRQ
> at the hardware.
Please ignore my suggested patch. I just saw Ingo's commit that
modified the default_disable().
Kevin
>
> Kevin
>
>
> commit f9b534f23ac7835eead99fb0a9cec7c505fe1e85
> Author: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
> Date: Tue May 5 17:32:59 2009 -0700
>
> IRQ: chip->disable should default to chip->mask if NULL
>
> The struct irq_chip comments in <linux/irq.h> state:
>
> * @disable: disable the interrupt (defaults to chip->mask if NULL)
>
> However, the code in kernel/irq/chip.c does otherwise by setting
> a NULL disable hook to an empty default_disable function.
>
> This patch makes the default_disable function call the ->mask hook
> to match the comments.
>
> Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
>
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> index c687ba4..0fb690a 100644
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -238,6 +238,10 @@ static void default_enable(unsigned int irq)
> */
> static void default_disable(unsigned int irq)
> {
> + struct irq_desc *desc = irq_to_desc(irq);
> +
> + desc->chip->mask(irq);
> + desc->status |= IRQ_MASKED;
> }
>
> /*
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