Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v3 7/7] clocksource/drivers/arm_arch_timer: validate arch_timer_rate | Date | Fri, 14 Feb 2020 01:35:58 +0100 |
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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
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