linux-kernel - [PATCH] clocksource/drivers/timer-riscv: Drop extra CSR write

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Date: Tue, 12 Mar 2024 12:32:47 -0700
From: Samuel Holland <samuel.holland@...ive.com>
To: Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc: Samuel Holland <samuel.holland@...ive.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org
Subject: [PATCH] clocksource/drivers/timer-riscv: Drop extra CSR write

On riscv32, the time comparator value is split across two CSRs. We write
both when stopping the timer, but realistically the time is just as
unlikely to reach 0xffffffff00000000 as 0xffffffffffffffff, so there is
no need to write the low CSR.

Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

 drivers/clocksource/timer-riscv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
index e66dcbd66566..eaaf01f3c34b 100644
--- a/drivers/clocksource/timer-riscv.c
+++ b/drivers/clocksource/timer-riscv.c
@@ -35,9 +35,10 @@ static bool riscv_timer_cannot_wake_cpu;
 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
+			csr_write(CSR_STIMECMP, ULONG_MAX);
 	} else {
 		sbi_set_timer(U64_MAX);
 	}
-- 
2.43.1