linux-kernel - Re: [PATCH v2] PM / Domains: Keep the pd status during system PM phases

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Date:   Fri, 20 Jan 2017 14:16:55 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Elaine Zhang <zhangqing@...k-chips.com>
Cc:     Feng Xiao <xf@...k-chips.com>, Heiko Stuebner <heiko@...ech.de>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>, Pavel Machek <pavel@....cz>,
        Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        Tao Huang <huangtao@...k-chips.com>, xxx@...k-chips.com,
        Caesar Wang <wxt@...k-chips.com>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] PM / Domains: Keep the pd status during system PM phases

On 20 January 2017 at 03:21, Elaine Zhang <zhangqing@...k-chips.com> wrote:
> If a PM domain is powered off before system suspend,
> we hope do nothing in system runtime suspend noirq phase
> and system runtime resume noirq phase.

One can hope, but that isn't good enough. :-)


>
> This modify is to slove system resume issue for RK3399.
> RK3399 SOC pd_gpu have voltage domain vdd_gpu,
> so we must follow open vdd_gpu and power on pd_gpu,
> power off pd_gpu and disable vdd_gpu.
> Fix up in runtime resume noirq phase power on all PDs.

This doesn't make any sense to me. Can please try to explain this is
in great more detail, then I can try to help.

>
> Signed-off-by: Elaine Zhang <zhangqing@...k-chips.com>
> ---
>  drivers/base/power/domain.c | 10 +++++++---
>  include/linux/pm_domain.h   |  1 +
>  2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 5711708532db..81351eec570f 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -842,8 +842,10 @@ static int pm_genpd_prepare(struct device *dev)
>
>         genpd_lock(genpd);
>
> -       if (genpd->prepared_count++ == 0)
> +       if (genpd->prepared_count++ == 0) {
>                 genpd->suspended_count = 0;
> +               genpd->suspend_power_off = genpd->status == GPD_STATE_POWER_OFF;
> +       }
>
>         genpd_unlock(genpd);
>
> @@ -877,7 +879,8 @@ static int pm_genpd_suspend_noirq(struct device *dev)
>         if (IS_ERR(genpd))
>                 return -EINVAL;
>
> -       if (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))
> +       if (genpd->suspend_power_off ||
> +           (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
>                 return 0;

This isn't going to work, because the PM domain might have been powered on.

There is simply no guarantee to that the PM domain remains powered off
during the system PM suspend phases. For example, any device in the PM
domain that get runtime resumed after the ->prepare() callback is
invoked this, will of course also trigger the PM domain to be powered
on.

>
>         if (genpd->dev_ops.stop && genpd->dev_ops.start) {
> @@ -914,7 +917,8 @@ static int pm_genpd_resume_noirq(struct device *dev)
>         if (IS_ERR(genpd))
>                 return -EINVAL;
>
> -       if (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))
> +       if (genpd->suspend_power_off ||
> +           (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
>                 return 0;

Ditto, for the same reasons as above.

>
>         /*
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 81ece61075df..9c0dc364f089 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -62,6 +62,7 @@ struct generic_pm_domain {
>         unsigned int device_count;      /* Number of devices */
>         unsigned int suspended_count;   /* System suspend device counter */
>         unsigned int prepared_count;    /* Suspend counter of prepared devices */
> +       bool suspend_power_off; /* Power status before system suspend */
>         int (*power_off)(struct generic_pm_domain *domain);
>         int (*power_on)(struct generic_pm_domain *domain);
>         struct gpd_dev_ops dev_ops;
> --
> 1.9.1
>
>

Kind regards
Uffe