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Message-Id: <20221201123954.1111603-2-apatel@ventanamicro.com>
Date: Thu, 1 Dec 2022 18:09:52 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Palmer Dabbelt <palmer@...belt.com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Thomas Gleixner <tglx@...utronix.de>
Cc: Andrew Jones <ajones@...tanamicro.com>,
Atish Patra <atishp@...shpatra.org>,
Samuel Holland <samuel@...lland.org>,
Conor Dooley <conor.dooley@...rochip.com>,
Anup Patel <anup@...infault.org>, devicetree@...r.kernel.org,
linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH v5 1/3] RISC-V: time: initialize hrtimer based broadcast clock event device
From: Conor Dooley <conor.dooley@...rochip.com>
Similarly to commit 022eb8ae8b5e ("ARM: 8938/1: kernel: initialize
broadcast hrtimer based clock event device"), RISC-V needs to initiate
hrtimer based broadcast clock event device before C3STOP can be used.
Otherwise, the introduction of C3STOP for the RISC-V arch timer in
commit 232ccac1bd9b ("clocksource/drivers/riscv: Events are stopped
during CPU suspend") leaves us without any broadcast timer registered.
This prevents the kernel from entering oneshot mode, which breaks timer
behaviour, for example clock_nanosleep().
A test app that sleeps each cpu for 6, 5, 4, 3 ms respectively, HZ=250
& C3STOP enabled, the sleep times are rounded up to the next jiffy:
== CPU: 1 == == CPU: 2 == == CPU: 3 == == CPU: 4 ==
Mean: 7.974992 Mean: 7.976534 Mean: 7.962591 Mean: 3.952179
Std Dev: 0.154374 Std Dev: 0.156082 Std Dev: 0.171018 Std Dev: 0.076193
Hi: 9.472000 Hi: 10.495000 Hi: 8.864000 Hi: 4.736000
Lo: 6.087000 Lo: 6.380000 Lo: 4.872000 Lo: 3.403000
Samples: 521 Samples: 521 Samples: 521 Samples: 521
Link: https://lore.kernel.org/linux-riscv/YzYTNQRxLr7Q9JR0@spud/
Fixes: 232ccac1bd9b ("clocksource/drivers/riscv: Events are stopped during CPU suspend")
Suggested-by: Samuel Holland <samuel@...lland.org>
Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
Reviewed-by: Samuel Holland <samuel@...lland.org>
Acked-by: Palmer Dabbelt <palmer@...osinc.com>
---
arch/riscv/kernel/time.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/riscv/kernel/time.c b/arch/riscv/kernel/time.c
index 8217b0f67c6c..1cf21db4fcc7 100644
--- a/arch/riscv/kernel/time.c
+++ b/arch/riscv/kernel/time.c
@@ -5,6 +5,7 @@
*/
#include <linux/of_clk.h>
+#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/delay.h>
#include <asm/sbi.h>
@@ -29,6 +30,8 @@ void __init time_init(void)
of_clk_init(NULL);
timer_probe();
+
+ tick_setup_hrtimer_broadcast();
}
void clocksource_arch_init(struct clocksource *cs)
--
2.34.1
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