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From: Marc Zyngier <maz@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, daniel.lezcano@linaro.org,
	linux-kernel@vger.kernel.org, tglx@linutronix.de
Subject: Re: [PATCH] clocksource/drivers/arm_arch_timer: Initialize evtstrm after finalizing cpucaps
Date: Mon, 18 Sep 2023 12:11:14 +0100	[thread overview]
Message-ID: <864jjrenxp.wl-maz@kernel.org> (raw)
In-Reply-To: <20230907133410.3817800-1-mark.rutland@arm.com>

On Thu, 07 Sep 2023 14:34:10 +0100,
Mark Rutland <mark.rutland@arm.com> wrote:
> 
> We attempt to initialize each CPU's arch_timer event stream in
> arch_timer_evtstrm_enable(), which we call from the
> arch_timer_starting_cpu() cpu hotplug callback which is registered early
> in boot. As this is registered before we initialize the system cpucaps,
> the test for ARM64_HAS_ECV will always be false for CPUs present at boot
> time, and will only be taken into account for CPUs onlined late
> (including those which are hotplugged out and in again).
> 
> Due to this, CPUs present and boot time may not use the intended divider
> and scale factor to generate the event stream, and may differ from other
> CPUs.
> 
> Correct this by only initializing the event stream after cpucaps have been
> finalized, registering a separate CPU hotplug callback for the event stream
> configuration. Since the caps must be finalized by this point, use
> spus_have_final_cap() to verify this.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

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WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, daniel.lezcano@linaro.org,
	linux-kernel@vger.kernel.org, tglx@linutronix.de
Subject: Re: [PATCH] clocksource/drivers/arm_arch_timer: Initialize evtstrm after finalizing cpucaps
Date: Mon, 18 Sep 2023 12:11:14 +0100	[thread overview]
Message-ID: <864jjrenxp.wl-maz@kernel.org> (raw)
In-Reply-To: <20230907133410.3817800-1-mark.rutland@arm.com>

On Thu, 07 Sep 2023 14:34:10 +0100,
Mark Rutland <mark.rutland@arm.com> wrote:
> 
> We attempt to initialize each CPU's arch_timer event stream in
> arch_timer_evtstrm_enable(), which we call from the
> arch_timer_starting_cpu() cpu hotplug callback which is registered early
> in boot. As this is registered before we initialize the system cpucaps,
> the test for ARM64_HAS_ECV will always be false for CPUs present at boot
> time, and will only be taken into account for CPUs onlined late
> (including those which are hotplugged out and in again).
> 
> Due to this, CPUs present and boot time may not use the intended divider
> and scale factor to generate the event stream, and may differ from other
> CPUs.
> 
> Correct this by only initializing the event stream after cpucaps have been
> finalized, registering a separate CPU hotplug callback for the event stream
> configuration. Since the caps must be finalized by this point, use
> spus_have_final_cap() to verify this.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Marc Zyngier <maz@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>

Acked-by: Marc Zyngier <maz@kernel.org>

	M.

-- 
Without deviation from the norm, progress is not possible.

  parent reply	other threads:[~2023-09-18 11:11 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-07 13:34 [PATCH] clocksource/drivers/arm_arch_timer: Initialize evtstrm after finalizing cpucaps Mark Rutland
2023-09-07 13:34 ` Mark Rutland
2023-09-15 19:14 ` Thomas Gleixner
2023-09-15 19:14   ` Thomas Gleixner
2023-09-18 11:11 ` Marc Zyngier [this message]
2023-09-18 11:11   ` Marc Zyngier
2023-10-11  8:30 ` Daniel Lezcano
2023-10-11  8:30   ` Daniel Lezcano
2023-10-11  9:36   ` Mark Rutland
2023-10-11  9:36     ` Mark Rutland
2023-10-11 10:06     ` Daniel Lezcano
2023-10-11 10:06       ` Daniel Lezcano
2023-10-11 10:42       ` Mark Rutland
2023-10-11 10:42         ` Mark Rutland

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