diff options
| author | Marc Zyngier <maz@kernel.org> | 2021-10-17 13:42:19 +0100 |
|---|---|---|
| committer | Daniel Lezcano <daniel.lezcano@linaro.org> | 2021-10-17 21:47:44 +0200 |
| commit | ec8f7f3342c88780d682cc2464daf0fe43259c4f (patch) | |
| tree | 864a230409e65b903c5545d332b1c0b308124ae3 /arch/arm64/include/asm/arch_timer.h | |
| parent | 41f8d02a6a558f80775bf61fe6312a14eeabbca0 (diff) | |
clocksource/drivers/arm_arch_timer: Drop unnecessary ISB on CVAL programming
Switching from TVAL to CVAL has a small drawback: we need an ISB
before reading the counter. We cannot get rid of it, but we can
instead remove the one that comes just after writing to CVAL.
This reduces the number of ISBs from 3 to 2 when programming
the timer.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211017124225.3018098-12-maz@kernel.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Diffstat (limited to 'arch/arm64/include/asm/arch_timer.h')
| -rw-r--r-- | arch/arm64/include/asm/arch_timer.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h index 4f4aa13dd01e..b8000ef71a2c 100644 --- a/arch/arm64/include/asm/arch_timer.h +++ b/arch/arm64/include/asm/arch_timer.h @@ -95,6 +95,7 @@ void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u64 val) switch (reg) { case ARCH_TIMER_REG_CTRL: write_sysreg(val, cntp_ctl_el0); + isb(); break; case ARCH_TIMER_REG_CVAL: write_sysreg(val, cntp_cval_el0); @@ -106,6 +107,7 @@ void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u64 val) switch (reg) { case ARCH_TIMER_REG_CTRL: write_sysreg(val, cntv_ctl_el0); + isb(); break; case ARCH_TIMER_REG_CVAL: write_sysreg(val, cntv_cval_el0); @@ -116,8 +118,6 @@ void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u64 val) } else { BUILD_BUG(); } - - isb(); } static __always_inline |