From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Shier <pshier@google.com>,
Raghavendra Rao Ananta <rananta@google.com>,
Ricardo Koller <ricarkol@google.com>,
Oliver Upton <oupton@google.com>, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Linus Walleij <linus.walleij@linaro.org>,
kernel-team@android.com
Subject: [PATCH 10/13] clocksource/arm_arch_timer: Drop unnecessary ISB on CVAL programming
Date: Mon, 9 Aug 2021 16:26:48 +0100 [thread overview]
Message-ID: <20210809152651.2297337-11-maz@kernel.org> (raw)
In-Reply-To: <20210809152651.2297337-1-maz@kernel.org>
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>
---
arch/arm/include/asm/arch_timer.h | 4 ++--
arch/arm64/include/asm/arch_timer.h | 4 ++--
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm/include/asm/arch_timer.h b/arch/arm/include/asm/arch_timer.h
index f014630259cb..787a98ed0716 100644
--- a/arch/arm/include/asm/arch_timer.h
+++ b/arch/arm/include/asm/arch_timer.h
@@ -31,6 +31,7 @@ void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u64 val)
switch (reg) {
case ARCH_TIMER_REG_CTRL:
asm volatile("mcr p15, 0, %0, c14, c2, 1" : : "r" ((u32)val));
+ isb();
break;
case ARCH_TIMER_REG_CVAL:
asm volatile("mcrr p15, 2, %Q0, %R0, c14" : : "r" (val));
@@ -40,14 +41,13 @@ void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u64 val)
switch (reg) {
case ARCH_TIMER_REG_CTRL:
asm volatile("mcr p15, 0, %0, c14, c3, 1" : : "r" ((u32)val));
+ isb();
break;
case ARCH_TIMER_REG_CVAL:
asm volatile("mcrr p15, 3, %Q0, %R0, c14" : : "r" (val));
break;
}
}
-
- isb();
}
static __always_inline
diff --git a/arch/arm64/include/asm/arch_timer.h b/arch/arm64/include/asm/arch_timer.h
index 861cafc4aca5..b2f056db1225 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);
@@ -104,14 +105,13 @@ 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);
break;
}
}
-
- isb();
}
static __always_inline
--
2.30.2
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next prev parent reply other threads:[~2021-08-09 16:00 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-09 15:26 [PATCH 00/13] clocksource/arm_arch_timer: Add basic ARMv8.6 support Marc Zyngier
2021-08-09 15:26 ` [PATCH 01/13] clocksource/arm_arch_timer: Drop CNT*_TVAL read accessors Marc Zyngier
2021-08-11 7:02 ` Oliver Upton
2021-08-24 16:20 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 02/13] clocksource/arm_arch_timer: Extend write side of timer register accessors to u64 Marc Zyngier
2021-08-09 16:12 ` Oliver Upton
2021-08-24 16:20 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 03/13] clocksource/arm_arch_timer: Move system register timer programming over to CVAL Marc Zyngier
2021-08-11 7:15 ` Oliver Upton
2021-08-24 16:21 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 04/13] clocksource/arm_arch_timer: Move drop _tval from erratum function names Marc Zyngier
2021-08-09 16:16 ` Oliver Upton
2021-08-24 16:29 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 05/13] clocksource/arm_arch_timer: Fix MMIO base address vs callback ordering issue Marc Zyngier
2021-08-09 16:52 ` Oliver Upton
2021-08-10 8:27 ` Marc Zyngier
2021-08-24 16:44 ` Mark Rutland
2021-08-09 15:26 ` [PATCH 06/13] clocksource/arm_arch_timer: Move MMIO timer programming over to CVAL Marc Zyngier
2021-08-09 15:26 ` [PATCH 07/13] clocksource/arm_arch_timer: Advertise 56bit timer to the core code Marc Zyngier
2021-08-09 15:26 ` [PATCH 08/13] clocksource/arm_arch_timer: Work around broken CVAL implementations Marc Zyngier
2021-08-10 12:34 ` Mark Rutland
2021-08-10 13:15 ` Marc Zyngier
2021-08-09 15:26 ` [PATCH 09/13] clocksource/arm_arch_timer: Remove any trace of the TVAL programming interface Marc Zyngier
2021-08-09 15:26 ` Marc Zyngier [this message]
2021-08-09 15:26 ` [PATCH 11/13] clocksource/arm_arch_timer: Fix masking for high freq counters Marc Zyngier
2021-08-09 16:45 ` Oliver Upton
2021-08-10 8:40 ` Marc Zyngier
2021-08-10 9:09 ` Oliver Upton
2021-08-09 15:26 ` [PATCH 12/13] arm64: Add a capability for FEAT_EVC Marc Zyngier
2021-08-09 16:30 ` Oliver Upton
2021-08-09 16:34 ` Oliver Upton
2021-08-09 18:02 ` Marc Zyngier
2021-08-09 18:21 ` Oliver Upton
2021-08-09 18:23 ` Oliver Upton
2021-08-09 15:26 ` [PATCH 13/13] arm64: Add CNT{P, V}CTSS_EL0 alternatives to cnt{p, v}ct_el0 Marc Zyngier
2021-08-09 16:42 ` Oliver Upton
2021-08-09 18:11 ` Marc Zyngier
2021-08-09 18:17 ` Oliver Upton
2021-08-10 7:59 ` Marc Zyngier
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