linux-kernel - [PATCH 2/2] time-riscv: Stop stimecmp when cpu hotplug

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Message-Id: <20240829033904.477200-3-nick.hu@sifive.com>
Date: Thu, 29 Aug 2024 11:39:00 +0800
From: Nick Hu <nick.hu@...ive.com>
To: greentime.hu@...ive.com,
	zong.li@...ive.com,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Pavel Machek <pavel@....cz>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Jones <ajones@...tanamicro.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Nick Hu <nick.hu@...ive.com>,
	Sunil V L <sunilvl@...tanamicro.com>,
	linux-pm@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] time-riscv: Stop stimecmp when cpu hotplug

Stop the stimecmp when the cpu is going to be off otherwise the timer
interrupt may pending while performing power down operation.

Signed-off-by: Nick Hu <nick.hu@...ive.com>
---
 drivers/clocksource/timer-riscv.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index 48ce50c5f5e6..9a6acaa8dfb0 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -32,15 +32,19 @@
 static DEFINE_STATIC_KEY_FALSE(riscv_sstc_available);
 static bool riscv_timer_cannot_wake_cpu;
 
+static void riscv_clock_stop_stimecmp(void)
+{
+	csr_write(CSR_STIMECMP, ULONG_MAX);
+	if (IS_ENABLED(CONFIG_32BIT))
+		csr_write(CSR_STIMECMPH, ULONG_MAX);
+}
+
 static void riscv_clock_event_stop(void)
 {
-	if (static_branch_likely(&riscv_sstc_available)) {
-		csr_write(CSR_STIMECMP, ULONG_MAX);
-		if (IS_ENABLED(CONFIG_32BIT))
-			csr_write(CSR_STIMECMPH, ULONG_MAX);
-	} else {
+	if (static_branch_likely(&riscv_sstc_available))
+		riscv_clock_stop_stimecmp();
+	else
 		sbi_set_timer(U64_MAX);
-	}
 }
 
 static int riscv_clock_next_event(unsigned long delta,
@@ -126,7 +130,11 @@ static int riscv_timer_starting_cpu(unsigned int cpu)
 
 static int riscv_timer_dying_cpu(unsigned int cpu)
 {
-	disable_percpu_irq(riscv_clock_event_irq);
+	if (static_branch_likely(&riscv_sstc_available))
+		riscv_clock_stop_stimecmp();
+	else
+		disable_percpu_irq(riscv_clock_event_irq);
+
 	return 0;
 }
 
-- 
2.34.1