Re: [PATCH v10 21/27] drivers: firmware: psci: Add a helper to attach a CPU to its PM domain

[Lina Iyer]

On Thu, Nov 29 2018 at 10:50 -0700, Ulf Hansson wrote:
> Introduce a new PSCI DT helper function, psci_dt_attach_cpu(), which takes
> a CPU number as an in-parameter and attaches the CPU's struct device to its
> corresponding PM domain. Additionally, the helper prepares the CPU to be
> power managed via runtime PM, which is the last step needed to enable the
> interaction with the PM domain through the runtime PM callbacks.
>
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
> ---
>
> Changes in v10:
> 	- New patch: Replaces "PM / Domains: Add helper functions to
> 	  attach/detach CPUs to/from genpd".
>
> ---
> drivers/firmware/psci/psci.h           |  1 +
> drivers/firmware/psci/psci_pm_domain.c | 19 +++++++++++++++++++
> 2 files changed, 20 insertions(+)
>
> diff --git a/drivers/firmware/psci/psci.h b/drivers/firmware/psci/psci.h
> index 05af462cc96e..fbc9980dee69 100644
> --- a/drivers/firmware/psci/psci.h
> +++ b/drivers/firmware/psci/psci.h
> @@ -15,6 +15,7 @@ int psci_dt_parse_state_node(struct device_node *np, u32 *state);
> int psci_dt_init_pm_domains(struct device_node *np);
> int psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,
> 			struct device_node *cpu_node, u32 *psci_states);
> +int psci_dt_attach_cpu(int cpu);
> #else
> static inline int psci_dt_init_pm_domains(struct device_node *np) { return 0; }
> #endif
> diff --git a/drivers/firmware/psci/psci_pm_domain.c b/drivers/firmware/psci/psci_pm_domain.c
> index 6c9d6a644c7f..b0fa7da8a0ce 100644
> --- a/drivers/firmware/psci/psci_pm_domain.c
> +++ b/drivers/firmware/psci/psci_pm_domain.c
> @@ -12,8 +12,10 @@
> #include <linux/device.h>
> #include <linux/kernel.h>
> #include <linux/pm_domain.h>
> +#include <linux/pm_runtime.h>
> #include <linux/slab.h>
> #include <linux/string.h>
> +#include <linux/cpu.h>
> #include <linux/cpuidle.h>
> #include <linux/cpu_pm.h>
>
> @@ -367,4 +369,21 @@ int psci_dt_pm_domains_parse_states(struct cpuidle_driver *drv,
>
> 	return 0;
> }
> +
> +int psci_dt_attach_cpu(int cpu)
> +{
> +	struct device *dev = get_cpu_device(cpu);
> +	int ret;
> +
> +	ret = dev_pm_domain_attach(dev, true);
> +	if (ret)
> +		return ret;
> +
> +	pm_runtime_irq_safe(dev);
> +	pm_runtime_get_noresume(dev);
> +	pm_runtime_set_active(dev);
You would want to set this only if the CPU is online. Otherwise we will
not power down the domain, if the CPU was never brought online.
> +	pm_runtime_enable(dev);
> +
> +	return 0;
> +}
> #endif
> --
> 2.17.1