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SubjectRe: [PATCH v8 08/26] PM / Domains: Extend genpd CPU governor to cope with QoS constraints
Date
On Wednesday, June 20, 2018 7:22:08 PM CEST Ulf Hansson wrote:
> CPU devices and other regular devices may share the same PM domain and may
> also be hierarchically related via subdomains. In either case, all devices
> including CPUs, may be attached to a PM domain managed by genpd, that has
> an idle state with an enter/exit latency.
>
> Let's take these latencies into account in the state selection process by
> genpd's governor for CPUs. This means the governor, pm_domain_cpu_gov,
> becomes extended to satisfy both a state's residency and a potential dev PM
> QoS constraint.
>
> Cc: Lina Iyer <ilina@codeaurora.org>
> Co-developed-by: Lina Iyer <lina.iyer@linaro.org>
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
> drivers/base/power/domain_governor.c | 15 +++++++++++----
> include/linux/pm_domain.h | 1 +
> 2 files changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/power/domain_governor.c b/drivers/base/power/domain_governor.c
> index 1aad55719537..03d4e9454ce9 100644
> --- a/drivers/base/power/domain_governor.c
> +++ b/drivers/base/power/domain_governor.c
> @@ -214,8 +214,10 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
> struct generic_pm_domain *genpd = pd_to_genpd(pd);
> struct gpd_link *link;
>
> - if (!genpd->max_off_time_changed)
> + if (!genpd->max_off_time_changed) {
> + genpd->state_idx = genpd->cached_power_down_state_idx;
> return genpd->cached_power_down_ok;
> + }
>
> /*
> * We have to invalidate the cached results for the masters, so
> @@ -240,6 +242,7 @@ static bool default_power_down_ok(struct dev_pm_domain *pd)
> genpd->state_idx--;
> }
>
> + genpd->cached_power_down_state_idx = genpd->state_idx;
> return genpd->cached_power_down_ok;
> }
>
> @@ -255,6 +258,10 @@ static bool cpu_power_down_ok(struct dev_pm_domain *pd)
> s64 idle_duration_ns;
> int cpu, i;
>
> + /* Validate dev PM QoS constraints. */
> + if (!default_power_down_ok(pd))
> + return false;
> +
> if (!(genpd->flags & GENPD_FLAG_CPU_DOMAIN))
> return true;
>
> @@ -276,9 +283,9 @@ static bool cpu_power_down_ok(struct dev_pm_domain *pd)
> /*
> * Find the deepest idle state that has its residency value satisfied
> * and by also taking into account the power off latency for the state.
> - * Start at the deepest supported state.
> + * Start at the state picked by the dev PM QoS constraint validation.
> */
> - i = genpd->state_count - 1;
> + i = genpd->state_idx;
> do {
> if (!genpd->states[i].residency_ns)
> break;
> @@ -312,6 +319,6 @@ struct dev_power_governor pm_domain_always_on_gov = {
> };
>
> struct dev_power_governor pm_domain_cpu_gov = {
> - .suspend_ok = NULL,
> + .suspend_ok = default_suspend_ok,
> .power_down_ok = cpu_power_down_ok,
> };
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 97901c833108..dbc69721cad8 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -81,6 +81,7 @@ struct generic_pm_domain {
> s64 max_off_time_ns; /* Maximum allowed "suspended" time. */
> bool max_off_time_changed;
> bool cached_power_down_ok;
> + bool cached_power_down_state_idx;
> int (*attach_dev)(struct generic_pm_domain *domain,
> struct device *dev);
> void (*detach_dev)(struct generic_pm_domain *domain,
>

I don't see much value in splitting this patch off [07/26] and it actually
confused me, so it may as well confuse someone else.

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