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SubjectRe: [PATCH v2 0/3] renesas: irqchip: Use WAKEUP_PATH driver PM flag
Hi Rafael,

On Sun, Dec 31, 2017 at 12:47 PM, Rafael J. Wysocki <> wrote:
> On Sun, Dec 31, 2017 at 10:22 AM, Geert Uytterhoeven
> <> wrote:
>> On Sun, Dec 31, 2017 at 1:56 AM, Rafael J. Wysocki <> wrote:
>>> On Fri, Dec 29, 2017 at 2:31 PM, Ulf Hansson <> wrote:
>>>> From: Geert Uytterhoeven <>
>>>> Changes in v2: [By Ulf Hansson]
>>>> - I have picked up the series from Geert [1] and converted it into use
>>>> the WAKEUP_PATH driver PM flag. This includes some minor changes to each
>>>> patch and updates to the changelogs.
>>>> - An important note, the WAKEUP_PATH driver PM flag is introduced in a
>>>> separate series [2], not yet applied, so @subject series depends on it.
>>>> - One more note, two of the patches has a checkpatch error, however I
>>>> did not fix them, becuase I think that should be done separate.
>>>> [1]
>>>> [2]
>>>> More information below, picked from Geert's previous cover letter.
>>>> Kind regards
>>>> Uffe
>>>> Hi all,
>>>> If an interrupt controller in a Renesas ARM SoC is part of a Clock
>>>> Domain, and it is part of the wakeup path, it must be kept active during
>>>> system suspend.
>>>> Currently this is handled in all interrupt controller drivers by
>>>> explicitly increasing the use count of the module clock when the device
>>>> is part of the wakeup path. However, this explicit clock handling is
>>>> merely a workaround for a failure to properly communicate wakeup
>>>> information to the device core.
>>>> Hence this series fixes the affected drivers by setting the devices'
>>>> power.wakeup_path fields instead, to indicate they are part of the
>>>> wakeup path. Depending on the PM Domain's active_wakeup configuration,
>>>> the genpd core code will keep the device enabled (and the clock running)
>>>> during system suspend when needed.
>>> However, there is a convention, documented in the kerneldoc comment of
>>> device_init_wakeup(), by which devices participating in system wakeup
>>> "passively" (like USB controllers and hubs) are expected to have it
>>> enabled by default.
>>> If that convention was followed by the devices in question here, the
>>> wakeup_path bit would be set for them and no other code changes would
>>> be necessary. So is there any reason for not following it?
>> Yes there is. The need to stay enabled during system suspend depends
>> on the consumer of the interrupt. It is controlled by the consumer using
>> the irq_chip.irq_set_wake() callback at runtime, and may change at runtime.
>> If the wakeup_path flag is always set, the interrupt controller will
>> never be suspended during system suspend, and thus waste power.
> OK
> For IRQ chips in particular, I think, you don't need add new fields to
> struct dev_pm_info to make it work.
> In ->suspend (or ->suspend_late, which may be better) you can check
> the IRQD_WAKEUP_STATE flag of the irq_desc associated with the pin.
> If that is set, you can simply set power.wakeup_path for the device
> and that will make genpd skip it. Wouldn't that work?

The irq_desc is per pin, while suspend is called per platform device, which
contains one or more irq_chips, each serving one or more pins.
So checking for IRQD_WAKEUP_STATE means looping over all irq_descs
associated to the platform device.

Which made me realize {gpio_rcar,irqc,intc_irqpin}_priv.wakeup_path should
not be a flag, but a counter. Currently it works by luck, as we never have
two independent wake-up sources being routed through the same irqchip.



Geert Uytterhoeven -- There's lots of Linux beyond ia32 --

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

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