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From: Thomas Gleixner <tglx@linutronix.de>
To: Ionela Voinescu <ionela.voinescu@arm.com>,
	catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com,
	maz@kernel.org, suzuki.poulose@arm.com, sudeep.holla@arm.com,
	lukasz.luba@arm.com, valentin.schneider@arm.com,
	rjw@rjwysocki.net, ionela.voinescu@arm.com
Cc: peterz@infradead.org, mingo@redhat.com,
	vincent.guittot@linaro.org, viresh.kumar@linaro.org,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v3 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate
Date: Fri, 14 Feb 2020 01:35:58 +0100	[thread overview]
Message-ID: <87mu9mgg41.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200211184542.29585-8-ionela.voinescu@arm.com>

Ionela Voinescu <ionela.voinescu@arm.com> writes:

> From: Valentin Schneider <valentin.schneider@arm.com>
>
> Using an arch timer with a frequency of less than 1MHz can result in an
> incorrect functionality of the system which assumes a reasonable rate.
>
> One example is the use of activity monitors for frequency invariance
> which uses the rate of the arch timer as the known rate of the constant
> cycle counter in computing its ratio compared to the maximum frequency
> of a CPU. For arch timer frequencies less than 1MHz this ratio could
> end up being 0 which is an invalid value for its use.
>
> Therefore, warn if the arch timer rate is below 1MHz which contravenes
> the recommended architecture interval of 1 to 50MHz.
>
> Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>

So this patch is from Valentin. Where is his Signed-off-by?

>  
> +static int validate_timer_rate(void)
> +{
> +	if (!arch_timer_rate)
> +		return -EINVAL;
> +
> +	/* Arch timer frequency < 1MHz can cause trouble */
> +	WARN_ON(arch_timer_rate < 1000000);

This does not make sense to me. If the rate is out of bounds then why
warn an just continue instead of making it fail?

Thanks,

        tglx

  parent reply	other threads:[~2020-02-14  0:36 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-11 18:45 [PATCH v3 0/7] arm64: ARMv8.4 Activity Monitors support Ionela Voinescu
2020-02-11 18:45 ` [PATCH v3 1/7] arm64: add support for the AMU extension v1 Ionela Voinescu
2020-02-12 11:30   ` Suzuki Kuruppassery Poulose
2020-02-12 14:54     ` Valentin Schneider
2020-02-12 16:10     ` Ionela Voinescu
2020-02-12 16:20       ` Suzuki Kuruppassery Poulose
2020-02-12 18:20         ` Ionela Voinescu
2020-02-12 19:24           ` Suzuki K Poulose
2020-02-12 20:19         ` Ionela Voinescu
2020-02-12 16:24       ` Vladimir Murzin
2020-02-12 18:27         ` Ionela Voinescu
2020-02-11 18:45 ` [PATCH v3 2/7] arm64: trap to EL1 accesses to AMU counters from EL0 Ionela Voinescu
2020-02-12 11:44   ` Suzuki Kuruppassery Poulose
2020-02-12 15:36   ` Valentin Schneider
2020-02-11 18:45 ` [PATCH v3 3/7] arm64/kvm: disable access to AMU registers from kvm guests Ionela Voinescu
2020-02-12 15:36   ` Valentin Schneider
2020-02-12 16:33   ` Suzuki Kuruppassery Poulose
2020-02-11 18:45 ` [PATCH v3 4/7] Documentation: arm64: document support for the AMU extension Ionela Voinescu
2020-02-12 15:36   ` Valentin Schneider
2020-02-11 18:45 ` [PATCH v3 5/7] cpufreq: add function to get the hardware max frequency Ionela Voinescu
2020-02-12  4:14   ` Viresh Kumar
2020-02-13 11:59   ` Valentin Schneider
2020-02-13 12:59     ` Ionela Voinescu
2020-02-13 15:22       ` Valentin Schneider
2020-02-11 18:45 ` [PATCH v3 6/7] arm64: use activity monitors for frequency invariance Ionela Voinescu
2020-02-12 18:59   ` Lukasz Luba
2020-02-13  9:47     ` Ionela Voinescu
2020-02-17 16:59   ` Valentin Schneider
2020-02-23 18:49     ` Ionela Voinescu
2020-02-11 18:45 ` [PATCH v3 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate Ionela Voinescu
2020-02-12  9:30   ` Valentin Schneider
2020-02-12 10:32     ` Ionela Voinescu
2020-02-12 10:01   ` Lukasz Luba
2020-02-12 10:12     ` Marc Zyngier
2020-02-12 10:54       ` Ionela Voinescu
2020-02-12 10:55       ` Lukasz Luba
2020-02-12 11:10         ` Marc Zyngier
2020-02-12 11:43           ` Lukasz Luba
2020-02-12 11:12         ` Valentin Schneider
2020-02-14  0:35   ` Thomas Gleixner [this message]
2020-02-14 15:45     ` Ionela Voinescu
2020-02-14 15:57       ` Ionela Voinescu

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