linux-kernel - Re: [PATCH] clocksource/drivers/riscv: Events are stopped during CPU suspend

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Message-Id: <878D1D3C-E8F1-4B37-93F1-B3560E3F271E@jrtc27.com>
Date:   Mon, 9 May 2022 03:56:43 +0100
From:   Jessica Clarke <jrtc27@...c27.com>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Albert Ou <aou@...s.berkeley.edu>,
        Atish Patra <atishp@...shpatra.org>,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH] clocksource/drivers/riscv: Events are stopped during CPU
 suspend

On 9 May 2022, at 02:21, Samuel Holland <samuel@...lland.org> wrote:
> 
> Some implementations of the SBI time extension depend on hart-local
> state (for example, CSRs) that are lost or hardware that is powered
> down when a CPU is suspended. To be safe, the clockevents driver
> cannot assume that timer IRQs will be received during CPU suspend.
> 
> Fixes: 62b019436814 ("clocksource: new RISC-V SBI timer driver")

Surely that’s not right? A commit from 2018 can’t have been expected to
predict the future, I would expect this to be one of the patches adding
suspend to RISC-V which came years later.

Jess

> Signed-off-by: Samuel Holland <samuel@...lland.org>
> ---
> 
> drivers/clocksource/timer-riscv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> index 1767f8bf2013..593d5a957b69 100644
> --- a/drivers/clocksource/timer-riscv.c
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -34,7 +34,7 @@ static int riscv_clock_next_event(unsigned long delta,
> static unsigned int riscv_clock_event_irq;
> static DEFINE_PER_CPU(struct clock_event_device, riscv_clock_event) = {
> 	.name			= "riscv_timer_clockevent",
> -	.features		= CLOCK_EVT_FEAT_ONESHOT,
> +	.features		= CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP,
> 	.rating			= 100,
> 	.set_next_event		= riscv_clock_next_event,
> };
> -- 
> 2.35.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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