Re: [PATCH v2] clocksource: timer-riscv: Clear timer interrupt on timer initialization

[Anup Patel <anup@brainfault.org>]

On Mon, Jan 29, 2024 at 1:12 PM Ley Foon Tan
<leyfoon.tan@starfivetech.com> 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.
>
> Fixes: 9f7a8ff6391f ("RISC-V: Prefer sstc extension if available")
> Cc:  <stable@vger.kernel.org>
> Signed-off-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>

LGTM.

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

Regards,
Anup

>
> ---
> v2:
> Resolved comments from Anup.
> - Moved riscv_clock_event_stop() to riscv_timer_starting_cpu().
> - Added Fixes tag
> ---
>  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..672669eb7281 100644
> --- a/drivers/clocksource/timer-riscv.c
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -116,6 +116,9 @@ static int riscv_timer_starting_cpu(unsigned int cpu)
>                 ce->rating = 450;
>         clockevents_config_and_register(ce, riscv_timebase, 100, 0x7fffffff);
>
> +       /* Clear timer interrupt */
> +       riscv_clock_event_stop();
> +
>         enable_percpu_irq(riscv_clock_event_irq,
>                           irq_get_trigger_type(riscv_clock_event_irq));
>         return 0;
> --
> 2.43.0
>
>