linux-kernel - [PATCH v3] clocksource: timer-riscv: Clear timer interrupt on timer initialization

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Date: Thu,  7 Mar 2024 01:23:30 +0800
From: Ley Foon Tan <leyfoon.tan@...rfivetech.com>
To: Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Albert Ou <aou@...s.berkeley.edu>
Cc: atishp@...osinc.com,
	Samuel Holland <samuel.holland@...ive.com>,
	Anup Patel <apatel@...tanamicro.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Ley Foon Tan <lftan.linux@...il.com>,
	stable@...r.kernel.org
Subject: [PATCH v3] clocksource: timer-riscv: Clear timer interrupt on timer initialization

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@...r.kernel.org>
Signed-off-by: Ley Foon Tan <leyfoon.tan@...rfivetech.com>

---
v3:
Resolved comment from Samuel Holland.
- Function riscv_clock_event_stop() needs to be called before
  clockevents_config_and_register(), move riscv_clock_event_stop().

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..79bb9a98baa7 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -108,6 +108,9 @@ static int riscv_timer_starting_cpu(unsigned int cpu)
 {
 	struct clock_event_device *ce = per_cpu_ptr(&riscv_clock_event, cpu);
 
+	/* Clear timer interrupt */
+	riscv_clock_event_stop();
+
 	ce->cpumask = cpumask_of(cpu);
 	ce->irq = riscv_clock_event_irq;
 	if (riscv_timer_cannot_wake_cpu)
-- 
2.43.0