Re: [PATCH] clocksource: timer-riscv: Clear timer interrupt on timer initialization

[Anup Patel]

On Thu, Jan 25, 2024 at 10:25 PM Ley Foon Tan
<leyfoon.tan@xxxxxxxxxxxxxxxx> wrote:
>
> In the RISC-V specification, the stimecmp register doesn't have a default
> value. To prevent the timer interrupt from being triggered during timer
> initialization, clear the timer interrupt by writing stimecmp with a
> maximum value.
>
> Signed-off-by: Ley Foon Tan <leyfoon.tan@xxxxxxxxxxxxxxxx>
> ---
>  drivers/clocksource/timer-riscv.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> index e66dcbd66566..a75a74647344 100644
> --- a/drivers/clocksource/timer-riscv.c
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -172,6 +172,9 @@ static int __init riscv_timer_init_common(void)
>
>         sched_clock_register(riscv_sched_clock, 64, riscv_timebase);
>
> +       /* Clear timer interrupt */
> +       riscv_clock_event_stop();
> +

The riscv_timer_init_common() is called only on boot HART.

I suggest doing riscv_clock_event_stop() in riscv_timer_starting_cpu()
just before enable_percpu_irq().

I also suggest adding an appropriate Fixes tag in the commit description.

Regards,
Anup

>         error = request_percpu_irq(riscv_clock_event_irq,
>                                     riscv_timer_interrupt,
>                                     "riscv-timer", &riscv_clock_event);
> --
> 2.43.0
>
>
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