From: Conor Dooley conor.dooley@microchip.com
[ 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@sholland.org Signed-off-by: Conor Dooley conor.dooley@microchip.com Signed-off-by: Anup Patel apatel@ventanamicro.com Reviewed-by: Samuel Holland samuel@sholland.org Acked-by: Palmer Dabbelt palmer@rivosinc.com Link: https://lore.kernel.org/r/20230103141102.772228-2-apatel@ventanamicro.com Signed-off-by: Daniel Lezcano daniel.lezcano@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 15f4ab40e2221..50bb7e0d44ba3 100644 --- a/arch/riscv/kernel/time.c +++ b/arch/riscv/kernel/time.c @@ -13,6 +13,7 @@ */
#include <linux/of_clk.h> +#include <linux/clockchips.h> #include <linux/clocksource.h> #include <linux/delay.h> #include <asm/sbi.h> @@ -33,4 +34,6 @@ void __init time_init(void)
of_clk_init(NULL); timer_probe(); + + tick_setup_hrtimer_broadcast(); }