Subject: Re: [PATCH v3 5/7] drivers: firmware: psci: Add hierarchical domain idle states converter

From: Sudeep Holla <[email-masked]>
Date: Mon, 3 Feb 2020 17:08:32 +0000

On Mon, Feb 03, 2020 at 07:05:38PM +0530, Maulik Shah wrote:
> From: Ulf Hansson <[email-masked]>
>
> If the hierarchical CPU topology is used, but the OS initiated mode isn't
> supported, we need to rely solely on the regular cpuidle framework to
> manage the idle state selection, rather than using genpd and its
> governor.
>
> For this reason, introduce a new PSCI DT helper function,
> psci_dt_pm_domains_parse_states(), which parses and converts the
> hierarchically described domain idle states from DT, into regular flattened
> cpuidle states. The converted states are added to the existing cpuidle
> driver's array of idle states, which make them available for cpuidle.
>

And what's the main motivation for this if OSI is not supported in the
firmware ?

> Signed-off-by: Ulf Hansson <[email-masked]>
> [applied to new path, resolved conflicts]
> Signed-off-by: Maulik Shah <[email-masked]>
> ---
>  drivers/cpuidle/cpuidle-psci-domain.c | 137 +++++++++++++++++++++++++++++-----
>  drivers/cpuidle/cpuidle-psci.c        |  41 +++++-----
>  drivers/cpuidle/cpuidle-psci.h        |  11 +++
>  3 files changed, 153 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c
> index 423f03b..3c417f7 100644
> --- a/drivers/cpuidle/cpuidle-psci-domain.c
> +++ b/drivers/cpuidle/cpuidle-psci-domain.c
> @@ -26,13 +26,17 @@ struct psci_pd_provider {
>  };
>
>  static LIST_HEAD(psci_pd_providers);
> -static bool osi_mode_enabled __initdata;
> +static bool osi_mode_enabled;
>
>  static int psci_pd_power_off(struct generic_pm_domain *pd)
>  {
>  	struct genpd_power_state *state = &pd->states[pd->state_idx];
>  	u32 *pd_state;
>
> +	/* If we have failed to enable OSI mode, then abort power off. */
> +	if ((psci_has_osi_support()) && !osi_mode_enabled)
> +		return -EBUSY;
> +

Why is this needed ? IIUC we don't create genpd domains if OSI is not
enabled.

>  	if (!state->data)
>  		return 0;
>
> @@ -101,6 +105,105 @@ static void psci_pd_free_states(struct genpd_power_state *states,
>  	kfree(states);
>  }
>
> +static void psci_pd_convert_states(struct cpuidle_state *idle_state,
> +			u32 *psci_state, struct genpd_power_state *state)
> +{
> +	u32 *state_data = state->data;
> +	u64 target_residency_us = state->residency_ns;
> +	u64 exit_latency_us = state->power_on_latency_ns +
> +			state->power_off_latency_ns;
> +
> +	*psci_state = *state_data;
> +	do_div(target_residency_us, 1000);
> +	idle_state->target_residency = target_residency_us;
> +	do_div(exit_latency_us, 1000);
> +	idle_state->exit_latency = exit_latency_us;
> +	idle_state->enter = &psci_enter_domain_idle_state;
> +	idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
> +
> +	strncpy(idle_state->name, to_of_node(state->fwnode)->name,
> +		CPUIDLE_NAME_LEN - 1);
> +	strncpy(idle_state->desc, to_of_node(state->fwnode)->name,
> +		CPUIDLE_NAME_LEN - 1);
> +}
> +
> +static bool psci_pd_is_provider(struct device_node *np)
> +{
> +	struct psci_pd_provider *pd_prov, *it;
> +
> +	list_for_each_entry_safe(pd_prov, it, &psci_pd_providers, link) {
> +		if (pd_prov->node == np)
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
> +int __init psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,
> +			struct device_node *cpu_node, u32 *psci_states)
> +{
> +	struct genpd_power_state *pd_states;
> +	struct of_phandle_args args;
> +	int ret, pd_state_count, i, state_idx, psci_idx;
> +	u32 cpu_psci_state = psci_states[drv->state_count - 1];
> +	struct device_node *np = of_node_get(cpu_node);
> +
> +	/* Walk the CPU topology to find compatible domain idle states. */
> +	while (np) {
> +		ret = of_parse_phandle_with_args(np, "power-domains",
> +					"#power-domain-cells", 0, &args);
> +		of_node_put(np);
> +		if (ret)
> +			return 0;
> +
> +		np = args.np;
> +
> +		/* Verify that the node represents a psci pd provider. */
> +		if (!psci_pd_is_provider(np)) {
> +			of_node_put(np);
> +			return 0;
> +		}
> +
> +		/* Parse for compatible domain idle states. */
> +		ret = psci_pd_parse_states(np, &pd_states, &pd_state_count);
> +		if (ret) {
> +			of_node_put(np);
> +			return ret;
> +		}
> +
> +		i = 0;
> +		while (i < pd_state_count) {
> +
> +			state_idx = drv->state_count;
> +			if (state_idx >= CPUIDLE_STATE_MAX) {
> +				pr_warn("exceeding max cpuidle states\n");
> +				of_node_put(np);
> +				return 0;
> +			}
> +
> +			psci_idx = state_idx + i;
> +			psci_pd_convert_states(&drv->states[state_idx + i],
> +					&psci_states[psci_idx], &pd_states[i]);
> +
> +			/*
> +			 * In the hierarchical CPU topology the master PM domain
> +			 * idle state's DT property, "arm,psci-suspend-param",
> +			 * don't contain the bits for the idle state of the CPU,
> +			 * let's add those here.
> +			 */
> +			psci_states[psci_idx] |= cpu_psci_state;

No we can't do that. Refer previous discussions around that.

> +			pr_debug("psci-power-state %#x index %d\n",
> +				psci_states[psci_idx], psci_idx);
> +
> +			drv->state_count++;
> +			i++;
> +		}
> +		psci_pd_free_states(pd_states, pd_state_count);
> +	}
> +
> +	return 0;
> +}
> +
>  static int __init psci_pd_init(struct device_node *np)
>  {
>  	struct generic_pm_domain *pd;
> @@ -125,11 +228,14 @@ static int __init psci_pd_init(struct device_node *np)
>  	 * Parse the domain idle states and let genpd manage the state selection
>  	 * for those being compatible with "domain-idle-state".
>  	 */
> -	ret = psci_pd_parse_states(np, &states, &state_count);
> -	if (ret)
> -		goto free_name;
>
> -	pd->free_states = psci_pd_free_states;
> +	if (psci_has_osi_support()) {
> +		ret = psci_pd_parse_states(np, &states, &state_count);
> +		if (ret)
> +			goto free_name;
> +		pd->free_states = psci_pd_free_states;
> +	}
> +
>  	pd->name = kbasename(pd->name);
>  	pd->power_off = psci_pd_power_off;
>  	pd->states = states;
> @@ -236,10 +342,6 @@ static int __init psci_idle_init_domains(void)
>  	if (!np)
>  		return -ENODEV;
>
> -	/* Currently limit the hierarchical topology to be used in OSI mode. */
> -	if (!psci_has_osi_support())
> -		goto out;
> -
>  	/*
>  	 * Parse child nodes for the "#power-domain-cells" property and
>  	 * initialize a genpd/genpd-of-provider pair when it's found.
> @@ -265,14 +367,16 @@ static int __init psci_idle_init_domains(void)
>  		goto remove_pd;
>
>  	/* Try to enable OSI mode. */
> -	ret = psci_set_osi_mode();
> -	if (ret) {
> -		pr_warn("failed to enable OSI mode: %d\n", ret);
> -		psci_pd_remove_topology(np);
> -		goto remove_pd;
> +	if (psci_has_osi_support()) {
> +		ret = psci_set_osi_mode();
> +		if (ret) {
> +			pr_warn("failed to enable OSI mode: %d\n", ret);
> +			psci_pd_remove_topology(np);
> +			goto remove_pd;
> +		} else
> +			osi_mode_enabled = true;
>  	}
>
> -	osi_mode_enabled = true;
>  	of_node_put(np);
>  	pr_info("Initialized CPU PM domain topology\n");
>  	return pd_count;
> @@ -293,9 +397,6 @@ struct device __init *psci_dt_attach_cpu(int cpu)
>  {
>  	struct device *dev;
>
> -	if (!osi_mode_enabled)
> -		return NULL;
> -
>  	dev = dev_pm_domain_attach_by_name(get_cpu_device(cpu), "psci");
>  	if (IS_ERR_OR_NULL(dev))
>  		return dev;
> diff --git a/drivers/cpuidle/cpuidle-psci.c b/drivers/cpuidle/cpuidle-psci.c
> index edd7a54..3fa2aee 100644
> --- a/drivers/cpuidle/cpuidle-psci.c
> +++ b/drivers/cpuidle/cpuidle-psci.c
> @@ -49,7 +49,7 @@ static inline int psci_enter_state(int idx, u32 state)
>  	return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter, idx, state);
>  }
>
> -static int psci_enter_domain_idle_state(struct cpuidle_device *dev,
> +int psci_enter_domain_idle_state(struct cpuidle_device *dev,
>  					struct cpuidle_driver *drv, int idx)
>  {
>  	struct psci_cpuidle_data *data = this_cpu_ptr(&psci_cpuidle_data);
> @@ -193,24 +193,29 @@ static int __init psci_dt_cpu_init_idle(struct cpuidle_driver *drv,
>  		goto free_mem;
>  	}
>
> -	/* Currently limit the hierarchical topology to be used in OSI mode. */
> -	if (psci_has_osi_support()) {
> -		data->dev = psci_dt_attach_cpu(cpu);
> -		if (IS_ERR(data->dev)) {
> -			ret = PTR_ERR(data->dev);
> +	if (!psci_has_osi_support()) {
> +		ret = psci_dt_pm_domains_parse_states(drv, cpu_node,
> +					      psci_states);
> +		if (ret)
>  			goto free_mem;
> -		}
> -
> -		/*
> -		 * Using the deepest state for the CPU to trigger a potential
> -		 * selection of a shared state for the domain, assumes the
> -		 * domain states are all deeper states.
> -		 */
> -		if (data->dev) {
> -			drv->states[state_count - 1].enter =
> -				psci_enter_domain_idle_state;
> -			psci_cpuidle_use_cpuhp = true;
> -		}
> +	}
> +
> +	data->dev = psci_dt_attach_cpu(cpu);
> +	if (IS_ERR(data->dev)) {
> +		ret = PTR_ERR(data->dev);
> +		goto free_mem;
> +	}
> +
> +	/*
> +	 * Using the deepest state for the CPU to trigger a potential
> +	 * selection of a shared state for the domain, assumes the
> +	 * domain states are all deeper states.
> +	 */
> +
> +	if (data->dev) {
> +		drv->states[state_count - 1].enter =
> +			psci_enter_domain_idle_state;
> +		psci_cpuidle_use_cpuhp = true;
>  	}
>
>  	/* Idle states parsed correctly, store them in the per-cpu struct. */

--
Regards,
Sudeep

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