Re: [RFC v3 2/7] PM / Domains: support idle-states as genpd multiple-state.

[Zhaoyang Huang]

On 28 October 2015 at 01:40, Marc Titinger <mtitinger@xxxxxxxxxxxx> wrote:
> From: Marc Titinger <mtitinger@xxxxxxxxxxxx>
>
> This patch allows cluster-level idle-states to being soaked in as generic
> domain power states, in order for the domain governor to chose the most
> efficient power state compatible with the device constraints. Similarly,
> devices can register power-states into the cluster domain, in a manner
> consistent with idle-states.
>
> This is a attempt to address device-retention states for devices that
> are not hooked to runtime-pm, but feature a retention state handled by
> the same firmware that handles idle-states. For instance a L2 caches.
>
> With Juno, in this example the idle-state 'cluster-sleep-0 ' is known from
> each cluster generic domain, as the deepest sate.
>
> cat /sys/kernel/debug/pm_genpd/*
>
>   Domain             State name        Enter (ns) / Exit (ns)
> -------------------------------------------------------------
> a53_pd               cluster-sleep-0      1500000 / 800000
> a57_pd               cluster-sleep-0      1500000 / 800000
>
>     domain                      status pstate     slaves
>            /device                                      runtime status
> -----------------------------------------------------------------------
> a53_pd                          on
>     /devices/system/cpu/cpu0                            active
>     /devices/system/cpu/cpu3                            suspended
>     /devices/system/cpu/cpu4                            suspended
>     /devices/system/cpu/cpu5                            suspended
>     /devices/platform/D1                                suspended
> a57_pd                          cluster-sleep-0
>     /devices/system/cpu/cpu1                            suspended
>     /devices/system/cpu/cpu2                            suspended
>
> Signed-off-by: Marc Titinger <mtitinger+renesas@xxxxxxxxxxxx>
> ---
>  .../devicetree/bindings/power/power_domain.txt     |  29 ++++++
>  drivers/base/power/domain.c                        | 102 ++++++++++++++++++++-
>  include/linux/pm_domain.h                          |   3 +
>  3 files changed, 131 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/power/power_domain.txt b/Documentation/devicetree/bindings/power/power_domain.txt
> index 025b5e7..2657e19 100644
> --- a/Documentation/devicetree/bindings/power/power_domain.txt
> +++ b/Documentation/devicetree/bindings/power/power_domain.txt
> @@ -29,6 +29,16 @@ Optional properties:
>     specified by this binding. More details about power domain specifier are
>     available in the next section.
>
> + - cpu-idle-states : a phandle of an idle-state that shall be soaked into a
> +                 generic domain power state.
> +   CPU domains: Deep c-states that match a cluster power-off can be delegated to the
> +   generic power domain. Device other than CPUs may have register intermediate
> +   power states in the same domain. The domain governor can do a good job in
> +   electing a power state when the last cpu is powered off as devices in the
> +   same genpd may register intermediate states.
> +   Devices : a device may register an intermediate c-state matching a memory
> +   retention feature for instance.
> +
>  Example:
>
>         power: power-controller@12340000 {
> @@ -55,6 +65,25 @@ Example 2:
>                 #power-domain-cells = <1>;
>         };
>
> +Example 3:
> +
> +        pm-domains {
> +                a57_pd: a57_pd@ {
> +                        /* will have a57 platform ARM_PD_METHOD_OF_DECLARE*/
> +                        compatible = "arm,pd","arm,cortex-a57";
> +                        #power-domain-cells = <0>;
> +                        cpu-idle-states = <&CLUSTER_SLEEP_0>;
Should the "cpu_idle_states" be "domain-idle-states", which is
consistent to the following code.
> +                };
> +
> +                a53_pd: a53_pd@ {
> +                        /* will have a a53 platform ARM_PD_METHOD_OF_DECLARE*/
> +                        compatible = "arm,pd","arm,cortex-a53";
> +                        #power-domain-cells = <0>;
> +                        cpu-idle-states = <&CLUSTER_SLEEP_0>;
> +                };
> +        };
> +
> +
>  The nodes above define two power controllers: 'parent' and 'child'.
>  Domains created by the 'child' power controller are subdomains of '0' power
>  domain provided by the 'parent' power controller.
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index 6b2d771..8512e28 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -1345,7 +1345,8 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
>         else {
>                 dev_pm_qos_add_notifier(dev, &gpd_data->nb);
>                 atomic_inc(&genpd->usage_count);
> -               printk("Add device %d\n", atomic_read(&genpd->usage_count));
> +               dev_info(dev, "Add device %d\n",
> +                                       atomic_read(&genpd->usage_count));
>         }
>         return ret;
>  }
> @@ -1592,7 +1593,7 @@ static int state_cmp(const void *a, const void *b)
>  int pm_genpd_insert_state(struct generic_pm_domain *genpd,
>                 const struct genpd_power_state *state)
>  {
> -       int ret = 0;
> +       int i, ret = 0;
>         int state_count = genpd->state_count;
>
>         if (IS_ERR_OR_NULL(genpd) || (!state))
> @@ -1601,11 +1602,18 @@ int pm_genpd_insert_state(struct generic_pm_domain *genpd,
>         if (state_count >= GENPD_POWER_STATES_MAX)
>                 ret = -ENOMEM;
>
> +       /* Bail out, this state was already registered.*/
> +       for (i = 0; i < state_count; i++)
> +               if (!strncmp(state->name, genpd->states[i].name,
> +                       GENPD_MAX_NAME_SIZE))
> +                       return 0;
> +
>  #ifdef CONFIG_PM_ADVANCED_DEBUG
>         /* to save memory, Name allocation will happen if debug is enabled */
>         genpd->states[state_count].name = kstrndup(state->name,
>                         GENPD_MAX_NAME_SIZE,
>                         GFP_KERNEL);
> +
>         if (!genpd->states[state_count].name) {
>                 pr_err("%s Failed to allocate state '%s' name.\n",
>                                 genpd->name, state->name);
> @@ -1963,6 +1971,93 @@ static void genpd_dev_pm_sync(struct device *dev)
>         genpd_queue_power_off_work(pd);
>  }
>
> +
> +static int dt_cpuidle_to_genpd_power_state(struct genpd_power_state
> +                                          *genpd_state,
> +                                          struct device_node *state_node)
> +{
> +       int err = 0;
> +       u32 latency;
> +
> +       err = of_property_read_u32(state_node, "wakeup-latency-us", &latency);
> +       if (err) {
> +               u32 entry_latency, exit_latency;
> +
> +               err = of_property_read_u32(state_node, "entry-latency-us",
> +                                          &entry_latency);
> +               if (err) {
> +                       pr_debug(" * %s missing entry-latency-us property\n",
> +                                state_node->full_name);
> +                       return -EINVAL;
> +               }
> +
> +               err = of_property_read_u32(state_node, "exit-latency-us",
> +                                          &exit_latency);
> +               if (err) {
> +                       pr_debug(" * %s missing exit-latency-us property\n",
> +                                state_node->full_name);
> +                       return -EINVAL;
> +               }
> +               /*
> +                * If wakeup-latency-us is missing, default to entry+exit
> +                * latencies as defined in idle states bindings
> +                */
> +               latency = entry_latency + exit_latency;
> +       }
> +
> +       genpd_state->power_on_latency_ns = 1000 * latency;
> +
> +       err = of_property_read_u32(state_node, "entry-latency-us", &latency);
> +       if (err) {
> +               pr_debug(" * %s missing min-residency-us property\n",
> +                        state_node->full_name);
> +               return -EINVAL;
> +       }
> +
> +       genpd_state->power_off_latency_ns = 1000 * latency;
> +
> +       return 0;
> +}
> +
> +int of_genpd_device_parse_states(struct device_node *np,
> +                                struct generic_pm_domain *genpd)
> +{
> +       struct device_node *state_node;
> +       int i, err = 0;
> +
> +       for (i = 0;; i++) {
> +               struct genpd_power_state genpd_state;
> +
> +               state_node = of_parse_phandle(np, "domain-idle-states", i);
> +               if (!state_node)
> +                       break;
> +
> +               err = dt_cpuidle_to_genpd_power_state(&genpd_state,
> +                                                     state_node);
> +               if (err) {
> +                       pr_err
> +                           ("Parsing idle state node %s failed with err %d\n",
> +                            state_node->full_name, err);
> +                       err = -EINVAL;
> +                       break;
> +               }
> +#ifdef CONFIG_PM_ADVANCED_DEBUG
> +               genpd_state.name = kstrndup(state_node->name,
> +                                           GENPD_MAX_NAME_SIZE, GFP_KERNEL);
> +               if (!genpd_state.name)
> +                       err = -ENOMEM;
> +#endif
> +               of_node_put(state_node);
> +               err = pm_genpd_insert_state(genpd, &genpd_state);
> +               if (err)
> +                       break;
> +#ifdef CONFIG_PM_ADVANCED_DEBUG
> +               kfree(genpd_state.name);
> +#endif
> +       }
> +       return err;
> +}
> +
>  /**
>   * genpd_dev_pm_attach - Attach a device to its PM domain using DT.
>   * @dev: Device to attach.
> @@ -1996,7 +2091,6 @@ int genpd_dev_pm_attach(struct device *dev)
>         if (ret < 0) {
>                 if (ret != -ENOENT)
>                         return ret;
> -
>                 /*
>                  * Try legacy Samsung-specific bindings
>                  * (for backwards compatibility of DT ABI)
> @@ -2034,6 +2128,8 @@ int genpd_dev_pm_attach(struct device *dev)
>                 goto out;
>         }
>
> +       of_genpd_device_parse_states(pd_args.np, pd);
> +
>         dev->pm_domain->detach = genpd_dev_pm_detach;
>         dev->pm_domain->sync = genpd_dev_pm_sync;
>         ret = genpd_poweron(pd);
> diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
> index 24621be..48ab3b1 100644
> --- a/include/linux/pm_domain.h
> +++ b/include/linux/pm_domain.h
> @@ -248,6 +248,9 @@ struct generic_pm_domain *__of_genpd_xlate_onecell(
>                                         struct of_phandle_args *genpdspec,
>                                         void *data);
>
> +int of_genpd_device_parse_states(struct device_node *np,
> +       struct generic_pm_domain *genpd);
> +
>  int genpd_dev_pm_attach(struct device *dev);
>  #else /* !CONFIG_PM_GENERIC_DOMAINS_OF */
>  static inline int __of_genpd_add_provider(struct device_node *np,
> --
> 1.9.1
>
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