linux-kernel - Re: [PATCH] cpuidle: riscv-sbi: Allow cpuidle pd used by other devices

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Message-ID: <CAAhSdy0W5mSVp79dF63BJkDCE_tMxrxWOxqwaTHghztX6dEm2w@mail.gmail.com>
Date: Tue, 13 Aug 2024 17:55:44 +0530
From: Anup Patel <anup@...infault.org>
To: Nick Hu <nick.hu@...ive.com>
Cc: rafael@...nel.org, daniel.lezcano@...aro.org, paul.walmsley@...ive.com, 
	palmer@...belt.com, aou@...s.berkeley.edu, linux-pm@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	greentime.hu@...ive.com, zong.li@...ive.com, 
	Anup Patel <apatel@...tanamicro.com>
Subject: Re: [PATCH] cpuidle: riscv-sbi: Allow cpuidle pd used by other devices

On Tue, Aug 13, 2024 at 1:43 PM Nick Hu <nick.hu@...ive.com> wrote:
>
> To prevent the probe of consumer devices being deferred, create the
> platform devices for each pd node under '/cpus/power-domains' and move the
> driver initailization to the arch_initcall.

To prevent the probe deferral of consumer devices, you can simply use
fwnode_dev_initialized() instead of creating a dummy platform device.

> The consumer devices that inside the cpu/cluster power domain may register
> the genpd notifier where their power domains are point to the pd nodes
> under '/cpus/power-domains'. If the cpuidle.off==1, the genpd notifier
> will fail due to sbi_cpuidle_pd_allow_domain_state is not set. We also
> need the sbi_cpuidle_cpuhp_up/down to invoke the callbacks. Therefore,
> add a cpuidle_disabled() check before registering the cpuidle driver to
> address the issue.

I think dealing with cpuidle.off==1 case should be a separate patch.

>
> Signed-off-by: Nick Hu <nick.hu@...ive.com>
> Link: https://lore.kernel.org/lkml/20240226065113.1690534-1-nick.hu@sifive.com/
> Suggested-by: Anup Patel <apatel@...tanamicro.com>
> ---
>  drivers/cpuidle/cpuidle-riscv-sbi.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
> index a6e123dfe394..d6b01fc64f94 100644
> --- a/drivers/cpuidle/cpuidle-riscv-sbi.c
> +++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
> @@ -16,6 +16,7 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_platform.h>
>  #include <linux/slab.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_domain.h>
> @@ -25,6 +26,7 @@
>  #include <asm/smp.h>
>  #include <asm/suspend.h>
>
> +#include "cpuidle.h"
>  #include "dt_idle_states.h"
>  #include "dt_idle_genpd.h"
>
> @@ -336,6 +338,9 @@ static int sbi_cpuidle_init_cpu(struct device *dev, int cpu)
>                 return ret;
>         }
>
> +       if (cpuidle_disabled())
> +               return 0;
> +
>         ret = cpuidle_register(drv, NULL);
>         if (ret)
>                 goto deinit;
> @@ -380,20 +385,26 @@ static int sbi_cpuidle_pd_power_off(struct generic_pm_domain *pd)
>  struct sbi_pd_provider {
>         struct list_head link;
>         struct device_node *node;
> +       struct platform_device *pdev;
>  };
>
>  static LIST_HEAD(sbi_pd_providers);
>
>  static int sbi_pd_init(struct device_node *np)
>  {
> +       struct platform_device *pdev;
>         struct generic_pm_domain *pd;
>         struct sbi_pd_provider *pd_provider;
>         struct dev_power_governor *pd_gov;
>         int ret = -ENOMEM;
>
> +       pdev = of_platform_device_create(np, np->name, NULL);
> +       if (!pdev)
> +               goto out;
> +
>         pd = dt_idle_pd_alloc(np, sbi_dt_parse_state_node);
>         if (!pd)
> -               goto out;
> +               goto free_pdev;
>
>         pd_provider = kzalloc(sizeof(*pd_provider), GFP_KERNEL);
>         if (!pd_provider)
> @@ -419,6 +430,7 @@ static int sbi_pd_init(struct device_node *np)
>                 goto remove_pd;
>
>         pd_provider->node = of_node_get(np);
> +       pd_provider->pdev = pdev;
>         list_add(&pd_provider->link, &sbi_pd_providers);
>
>         pr_debug("init PM domain %s\n", pd->name);
> @@ -430,6 +442,8 @@ static int sbi_pd_init(struct device_node *np)
>         kfree(pd_provider);
>  free_pd:
>         dt_idle_pd_free(pd);
> +free_pdev:
> +       of_platform_device_destroy(&pdev->dev, NULL);
>  out:
>         pr_err("failed to init PM domain ret=%d %pOF\n", ret, np);
>         return ret;
> @@ -447,6 +461,7 @@ static void sbi_pd_remove(void)
>                 if (!IS_ERR(genpd))
>                         kfree(genpd);
>
> +               of_platform_device_destroy(&pd_provider->pdev->dev, NULL);
>                 of_node_put(pd_provider->node);
>                 list_del(&pd_provider->link);
>                 kfree(pd_provider);
> @@ -548,7 +563,10 @@ static int sbi_cpuidle_probe(struct platform_device *pdev)
>         /* Setup CPU hotplut notifiers */
>         sbi_idle_init_cpuhp();
>
> -       pr_info("idle driver registered for all CPUs\n");
> +       if (cpuidle_disabled())
> +               pr_info("cpuidle is disabled\n");
> +       else
> +               pr_info("idle driver registered for all CPUs\n");
>
>         return 0;
>
> @@ -592,4 +610,4 @@ static int __init sbi_cpuidle_init(void)
>
>         return 0;
>  }
> -device_initcall(sbi_cpuidle_init);
> +arch_initcall(sbi_cpuidle_init);
> --
> 2.34.1
>

Regards,
Anup