From: Samuel Holland <samuel.holland@sifive.com>
To: Ley Foon Tan <leyfoon.tan@starfivetech.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>
Cc: atishp@rivosinc.com, linux-riscv@lists.infradead.org,
linux-kernel@vger.kernel.org,
Ley Foon Tan <lftan.linux@gmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH v2] clocksource: timer-riscv: Clear timer interrupt on timer initialization
Date: Wed, 7 Feb 2024 12:11:48 -0600 [thread overview]
Message-ID: <22d7dcc9-a14a-4e96-bfee-dd358af0afd5@sifive.com> (raw)
In-Reply-To: <20240129072625.2837771-1-leyfoon.tan@starfivetech.com>
On 2024-01-29 1:26 AM, Ley Foon Tan 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>
>
> ---
> 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();
This change breaks boot on Unmatched. The bug is that the above call to
clockevents_config_and_register() sets the timer (see below), but the timer
interrupt never fires due to the added call to riscv_clock_event_stop(). You
need to move this line earlier in the function.
Here's the stack trace from the initial call to riscv_clock_next_event():
riscv_clock_next_event+0x12/0x3c
clockevents_program_event+0x9c/0x1c6
tick_setup_periodic+0x82/0x9e
tick_setup_device+0xa0/0xbe
tick_check_new_device+0x96/0xc6
clockevents_register_device+0xbe/0x128
clockevents_config_and_register+0x20/0x30
riscv_timer_starting_cpu+0xa2/0xec
cpuhp_invoke_callback+0x160/0x61e
cpuhp_issue_call+0x140/0x16e
__cpuhp_setup_state_cpuslocked+0x186/0x2b0
__cpuhp_setup_state+0x3a/0x60
riscv_timer_init_common+0xea/0x184
riscv_timer_init_dt+0xbe/0xc2
timer_probe+0x70/0xdc
time_init+0x74/0xa0
start_kernel+0x194/0x35e
Regards,
Samuel
> +
> enable_percpu_irq(riscv_clock_event_irq,
> irq_get_trigger_type(riscv_clock_event_irq));
> return 0;
prev parent reply other threads:[~2024-02-07 18:11 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-29 7:26 [PATCH v2] clocksource: timer-riscv: Clear timer interrupt on timer initialization Ley Foon Tan
2024-02-07 15:58 ` Anup Patel
2024-02-07 18:11 ` Samuel Holland [this message]
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