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

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Message-ID: <CAKddAkAOeoKZ9A7t4eK5JPN0xaVPBojCeY0X9khu-b=irE5=JQ@mail.gmail.com>
Date: Thu, 17 Jul 2025 15:24:51 +0800
From: Nick Hu <nick.hu@...ive.com>
To: Anup Patel <anup@...infault.org>
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 Thu, Jul 17, 2025 at 1:15 PM Anup Patel <anup@...infault.org> wrote:
>
> 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/
>
Will update it in the next version. Thanks

Regards,
Nick
> 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