linux-kernel - Re: [PATCH 1/6] PM: runtime: enable wake irq after runtime

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Date:   Fri, 9 Apr 2021 13:32:04 +0800
From:   Ikjoon Jang <ikjn@...omium.org>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        linux-usb@...r.kernel.org,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-pm@...r.kernel.org, Tony Lindgren <tony@...mide.com>,
        Tianping Fang <tianping.fang@...iatek.com>,
        Eddie Hung <eddie.hung@...iatek.com>,
        Nicolas Boichat <drinkcat@...omium.org>
Subject: Re: [PATCH 1/6] PM: runtime: enable wake irq after runtime_suspend
 hook called

Hi Chunfeng,

On Thu, Apr 8, 2021 at 5:35 PM Chunfeng Yun <chunfeng.yun@...iatek.com> wrote:
>
> When the dedicated wake irq is level trigger, enable it before
> calling runtime_suspend, will trigger an interrupt.
>
> e.g.
> for a low level trigger type, it's low level at running time (0),
> and becomes high level when enters suspend (runtime_suspend (1) is
> called), a wakeup signal at (2) make it become low level, wake irq
> will be triggered.
>
>                 ------------------
>                |           ^     ^|
> ----------------           |     | --------------
>  |<---(0)--->|<--(1)--|   (3)   (2)    (4)
>

Can't we just use a falling edge type for this irq line?

> if we enable the wake irq before calling runtime_suspend during (0),
> an interrupt will arise, it causes resume immediately;
> enable wake irq after calling runtime_suspend, e.g. at (3) or (4),
> will works.
>
> This patch seems no side effect on edge trigger wake irq.
>
> Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> ---
>  drivers/base/power/runtime.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index a46a7e30881b..796739a015a5 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -619,12 +619,12 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>         __update_runtime_status(dev, RPM_SUSPENDING);
>
>         callback = RPM_GET_CALLBACK(dev, runtime_suspend);
> -
> -       dev_pm_enable_wake_irq_check(dev, true);
>         retval = rpm_callback(callback, dev);
>         if (retval)
>                 goto fail;
>
> +       dev_pm_enable_wake_irq_check(dev, true);
> +
>   no_callback:
>         __update_runtime_status(dev, RPM_SUSPENDED);
>         pm_runtime_deactivate_timer(dev);
> @@ -659,7 +659,6 @@ static int rpm_suspend(struct device *dev, int rpmflags)
>         return retval;
>
>   fail:
> -       dev_pm_disable_wake_irq_check(dev);
>         __update_runtime_status(dev, RPM_ACTIVE);
>         dev->power.deferred_resume = false;
>         wake_up_all(&dev->power.wait_queue);
> --
> 2.18.0
>