This is a note to let you know that I've just added the patch titled RISC-V: time: initialize hrtimer based broadcast clock event device to the 6.2-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: risc-v-time-initialize-hrtimer-based-broadcast-clock.patch and it can be found in the queue-6.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit eb575fee6c9d473521ece722a1e8a05ecd752ad7 Author: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> Date: Tue Jan 3 19:41:00 2023 +0530 RISC-V: time: initialize hrtimer based broadcast clock event device [ Upstream commit 8b3b8fbb4896984b5564789a42240e4b3caddb61 ] 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@xxxxxxxxxxxx> Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> Signed-off-by: Anup Patel <apatel@xxxxxxxxxxxxxxxx> Reviewed-by: Samuel Holland <samuel@xxxxxxxxxxxx> Acked-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20230103141102.772228-2-apatel@xxxxxxxxxxxxxxxx Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/riscv/kernel/time.c b/arch/riscv/kernel/time.c index 8217b0f67c6cb..1cf21db4fcc77 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)