linux-kernel - Re: [PATCH 1/2] PM / Domains: Add GENPD_FLAG_SUSPEND

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Date:   Wed, 12 Aug 2020 11:45:06 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Andy Gross <agross@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Doug Anderson <dianders@...omium.org>,
        Kevin Hilman <khilman@...nel.org>
Subject: Re: [PATCH 1/2] PM / Domains: Add GENPD_FLAG_SUSPEND_ON flag

On Tue, 11 Aug 2020 at 21:03, Sibi Sankar <sibis@...eaurora.org> wrote:
>
> This is for power domains which needs to stay powered on for suspend
> but can be powered on/off as part of runtime PM. This flag is aimed at
> power domains coupled to remote processors which enter suspend states
> independent to that of the application processor. Such power domains
> are turned off only on remote processor crash/shutdown.

As Kevin also requested, please elaborate more on the use case.

Why exactly must the PM domain stay powered on during system suspend?
Is there a wakeup configured that needs to be managed - or is there a
co-processor/FW behaviour that needs to be obeyed to?

Kind regards
Uffe

>
> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
> ---
>  drivers/base/power/domain.c | 3 ++-
>  include/linux/pm_domain.h   | 5 +++++
>  2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 2cb5e04cf86cd..ba78ac4a450d4 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -129,6 +129,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
>  #define genpd_is_active_wakeup(genpd)  (genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
>  #define genpd_is_cpu_domain(genpd)     (genpd->flags & GENPD_FLAG_CPU_DOMAIN)
>  #define genpd_is_rpm_always_on(genpd)  (genpd->flags & GENPD_FLAG_RPM_ALWAYS_ON)
> +#define genpd_is_suspend_on(genpd)     (genpd->flags & GENPD_FLAG_SUSPEND_ON)
>
>  static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
>                 const struct generic_pm_domain *genpd)
> @@ -949,7 +950,7 @@ static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,
>  {
>         struct gpd_link *link;
>
> -       if (!genpd_status_on(genpd) || genpd_is_always_on(genpd))
> +       if (!genpd_status_on(genpd) || genpd_is_always_on(genpd) || genpd_is_suspend_on(genpd))
>                 return;
>
>         if (genpd->suspended_count != genpd->device_count
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index ee11502a575b0..3002a2d68936a 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -55,6 +55,10 @@
>   *
>   * GENPD_FLAG_RPM_ALWAYS_ON:   Instructs genpd to always keep the PM domain
>   *                             powered on except for system suspend.
> + *
> + * GENPD_FLAG_SUSPEND_ON:      Instructs genpd to keep the PM domain powered
> + *                             on during suspend and runtime PM controlled
> + *                             otherwise.
>   */
>  #define GENPD_FLAG_PM_CLK       (1U << 0)
>  #define GENPD_FLAG_IRQ_SAFE     (1U << 1)
> @@ -62,6 +66,7 @@
>  #define GENPD_FLAG_ACTIVE_WAKEUP (1U << 3)
>  #define GENPD_FLAG_CPU_DOMAIN   (1U << 4)
>  #define GENPD_FLAG_RPM_ALWAYS_ON (1U << 5)
> +#define GENPD_FLAG_SUSPEND_ON   (1U << 6)
>
>  enum gpd_status {
>         GPD_STATE_ACTIVE = 0,   /* PM domain is active */
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>