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From: Keqian Zhu <zhukeqian1@huawei.com>
To: <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<kvmarm@lists.cs.columbia.edu>, <kvm@vger.kernel.org>
Cc: Marc Zyngier <maz@kernel.org>,
	Steven Price <steven.price@arm.com>,
	"Andrew Jones" <drjones@redhat.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"Will Deacon" <will@kernel.org>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	<wanghaibin.wang@huawei.com>, Keqian Zhu <zhukeqian1@huawei.com>
Subject: [PATCH 2/2] clocksource: arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI
Date: Mon, 17 Aug 2020 20:24:15 +0800	[thread overview]
Message-ID: <20200817122415.6568-3-zhukeqian1@huawei.com> (raw)
In-Reply-To: <20200817122415.6568-1-zhukeqian1@huawei.com>

ARM virtual counter supports event stream, it can only trigger an event
when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 changes,
so the actual period of event stream is 2^(cntkctl_evnti + 1). For example,
when the trigger bit is 0, then virtual counter trigger an event for every
two cycles.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
---
 drivers/clocksource/arm_arch_timer.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 6e11c60..4140a37 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -794,10 +794,14 @@ static void arch_timer_configure_evtstream(void)
 {
 	int evt_stream_div, pos;
 
-	/* Find the closest power of two to the divisor */
-	evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ;
+	/*
+	 * Find the closest power of two to the divisor. As the event
+	 * stream can at most be generated at half the frequency of the
+	 * counter, use half the frequency when computing the divider.
+	 */
+	evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2;
 	pos = fls(evt_stream_div);
-	if (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))
+	if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))))
 		pos--;
 	/* enable event stream */
 	arch_timer_evtstrm_enable(min(pos, 15));
-- 
1.8.3.1


WARNING: multiple messages have this Message-ID (diff)
From: Keqian Zhu <zhukeqian1@huawei.com>
To: <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<kvmarm@lists.cs.columbia.edu>, <kvm@vger.kernel.org>
Cc: Marc Zyngier <maz@kernel.org>,
	Steven Price <steven.price@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Subject: [PATCH 2/2] clocksource: arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI
Date: Mon, 17 Aug 2020 20:24:15 +0800	[thread overview]
Message-ID: <20200817122415.6568-3-zhukeqian1@huawei.com> (raw)
In-Reply-To: <20200817122415.6568-1-zhukeqian1@huawei.com>

ARM virtual counter supports event stream, it can only trigger an event
when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 changes,
so the actual period of event stream is 2^(cntkctl_evnti + 1). For example,
when the trigger bit is 0, then virtual counter trigger an event for every
two cycles.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
---
 drivers/clocksource/arm_arch_timer.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 6e11c60..4140a37 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -794,10 +794,14 @@ static void arch_timer_configure_evtstream(void)
 {
 	int evt_stream_div, pos;
 
-	/* Find the closest power of two to the divisor */
-	evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ;
+	/*
+	 * Find the closest power of two to the divisor. As the event
+	 * stream can at most be generated at half the frequency of the
+	 * counter, use half the frequency when computing the divider.
+	 */
+	evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2;
 	pos = fls(evt_stream_div);
-	if (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))
+	if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))))
 		pos--;
 	/* enable event stream */
 	arch_timer_evtstrm_enable(min(pos, 15));
-- 
1.8.3.1

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Keqian Zhu <zhukeqian1@huawei.com>
To: <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<kvmarm@lists.cs.columbia.edu>, <kvm@vger.kernel.org>
Cc: Andrew Jones <drjones@redhat.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Marc Zyngier <maz@kernel.org>, Keqian Zhu <zhukeqian1@huawei.com>,
	Steven Price <steven.price@arm.com>,
	James Morse <james.morse@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	wanghaibin.wang@huawei.com, Will Deacon <will@kernel.org>
Subject: [PATCH 2/2] clocksource: arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI
Date: Mon, 17 Aug 2020 20:24:15 +0800	[thread overview]
Message-ID: <20200817122415.6568-3-zhukeqian1@huawei.com> (raw)
In-Reply-To: <20200817122415.6568-1-zhukeqian1@huawei.com>

ARM virtual counter supports event stream, it can only trigger an event
when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 changes,
so the actual period of event stream is 2^(cntkctl_evnti + 1). For example,
when the trigger bit is 0, then virtual counter trigger an event for every
two cycles.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
---
 drivers/clocksource/arm_arch_timer.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 6e11c60..4140a37 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -794,10 +794,14 @@ static void arch_timer_configure_evtstream(void)
 {
 	int evt_stream_div, pos;
 
-	/* Find the closest power of two to the divisor */
-	evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ;
+	/*
+	 * Find the closest power of two to the divisor. As the event
+	 * stream can at most be generated at half the frequency of the
+	 * counter, use half the frequency when computing the divider.
+	 */
+	evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2;
 	pos = fls(evt_stream_div);
-	if (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))
+	if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))))
 		pos--;
 	/* enable event stream */
 	arch_timer_evtstrm_enable(min(pos, 15));
-- 
1.8.3.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2020-08-17 12:24 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-17 12:24 [PATCH 0/2] clocksource: arm_arch_timer: Some fixes and code adjustment Keqian Zhu
2020-08-17 12:24 ` Keqian Zhu
2020-08-17 12:24 ` Keqian Zhu
2020-08-17 12:24 ` [PATCH 1/2] clocksource: arm_arch_timer: Simplify and fix count reader code logic Keqian Zhu
2020-08-17 12:24   ` Keqian Zhu
2020-08-17 12:24   ` Keqian Zhu
2020-08-17 12:52   ` Marc Zyngier
2020-08-17 12:52     ` Marc Zyngier
2020-08-17 12:52     ` Marc Zyngier
2020-08-18  1:40     ` zhukeqian
2020-08-18  1:40       ` zhukeqian
2020-08-18  1:40       ` zhukeqian
2020-08-17 12:24 ` Keqian Zhu [this message]
2020-08-17 12:24   ` [PATCH 2/2] clocksource: arm_arch_timer: Correct fault programming of CNTKCTL_EL1.EVNTI Keqian Zhu
2020-08-17 12:24   ` Keqian Zhu
2020-08-17 12:56   ` Marc Zyngier
2020-08-17 12:56     ` Marc Zyngier
2020-08-17 12:56     ` Marc Zyngier
2020-08-18  1:42     ` zhukeqian
2020-08-18  1:42       ` zhukeqian
2020-08-18  1:42       ` zhukeqian

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