linux-kernel - Re: [PATCH 1/2] irqchip/riscv-imsic: Restore the IMSIC registers

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Message-ID: <CAAhSdy2J6C8LvBCB0LKd2np47qBQ2EFXXnDvb2OjYKqSOF7EbQ@mail.gmail.com>
Date: Thu, 17 Jul 2025 10:45:01 +0530
From: Anup Patel <anup@...infault.org>
To: Nick Hu <nick.hu@...ive.com>
Cc: Alexandre Ghiti <alex@...ti.fr>, linux-riscv@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>
Subject: Re: [PATCH 1/2] irqchip/riscv-imsic: Restore the IMSIC registers

On Wed, Jul 9, 2025 at 8:26 AM Nick Hu <nick.hu@...ive.com> wrote:
>
> When the system woken up from the low power state, the IMSIC might be in
> the reset state. Therefore adding the CPU PM callbacks to restore the
> IMSIC register when the cpu resume from the low power state.
>
> Signed-off-by: Nick Hu <nick.hu@...ive.com>
> Reviewed-by: Yong-Xuan Wang <yongxuan.wang@...ive.com>
> Reviewed-by: Cyan Yang <cyan.yang@...ive.com>
> ---
>  drivers/irqchip/irq-riscv-imsic-early.c | 41 ++++++++++++++++++++-----
>  1 file changed, 33 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/irqchip/irq-riscv-imsic-early.c b/drivers/irqchip/irq-riscv-imsic-early.c
> index d9ae87808651..f64d9a0642bb 100644
> --- a/drivers/irqchip/irq-riscv-imsic-early.c
> +++ b/drivers/irqchip/irq-riscv-imsic-early.c
> @@ -7,6 +7,7 @@
>  #define pr_fmt(fmt) "riscv-imsic: " fmt
>  #include <linux/acpi.h>
>  #include <linux/cpu.h>
> +#include <linux/cpu_pm.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/irq.h>
> @@ -109,14 +110,8 @@ static void imsic_handle_irq(struct irq_desc *desc)
>         chained_irq_exit(chip, desc);
>  }
>
> -static int imsic_starting_cpu(unsigned int cpu)
> +static void imsic_restore(void)
>  {
> -       /* Mark per-CPU IMSIC state as online */
> -       imsic_state_online();
> -
> -       /* Enable per-CPU parent interrupt */
> -       enable_percpu_irq(imsic_parent_irq, irq_get_trigger_type(imsic_parent_irq));
> -
>         /* Setup IPIs */
>         imsic_ipi_starting_cpu();
>
> @@ -128,6 +123,19 @@ static int imsic_starting_cpu(unsigned int cpu)
>
>         /* Enable local interrupt delivery */
>         imsic_local_delivery(true);
> +}
> +
> +static int imsic_starting_cpu(unsigned int cpu)
> +{
> +       /* Mark per-CPU IMSIC state as online */
> +       imsic_state_online();
> +
> +       /* Enable per-CPU parent interrupt */
> +       enable_percpu_irq(imsic_parent_irq,
> +                         irq_get_trigger_type(imsic_parent_irq));
> +
> +       /* Restore the imsic reg */
> +       imsic_restore();
>
>         return 0;
>  }
> @@ -143,6 +151,23 @@ static int imsic_dying_cpu(unsigned int cpu)
>         return 0;
>  }
>
> +static int imsic_notifier(struct notifier_block *self, unsigned long cmd,
> +                         void *v)

s/imsic_notifier/imsic_pm_notifier/

The "void *v" parameter can be on the same line as function declaration.

> +{
> +       switch (cmd) {
> +       case CPU_PM_EXIT:
> +               /* Restore the imsic reg */
> +               imsic_restore();
> +               break;
> +       }
> +
> +       return NOTIFY_OK;
> +}
> +
> +static struct notifier_block imsic_notifier_block = {

s/imsic_notifier_block/imsic_pm_notifier_block/

> +       .notifier_call = imsic_notifier,
> +};
> +
>  static int __init imsic_early_probe(struct fwnode_handle *fwnode)
>  {
>         struct irq_domain *domain;
> @@ -180,7 +205,7 @@ static int __init imsic_early_probe(struct fwnode_handle *fwnode)
>         cpuhp_setup_state(CPUHP_AP_IRQ_RISCV_IMSIC_STARTING, "irqchip/riscv/imsic:starting",
>                           imsic_starting_cpu, imsic_dying_cpu);
>
> -       return 0;
> +       return cpu_pm_register_notifier(&imsic_notifier_block);
>  }
>
>  static int __init imsic_early_dt_init(struct device_node *node, struct device_node *parent)
> --
> 2.17.1
>

Otherwise, this looks good to me.

Reviewed-by: Anup Patel <anup@...infault.org>

Regards,
Anup