Re: [PATCH 15/17] arm64: arch_timer: Workaround for Cortex-A73 erratum 858921

From: Mark Rutland
Date: Mon Mar 20 2017 - 10:59:43 EST


On Mon, Mar 06, 2017 at 11:26:20AM +0000, Marc Zyngier wrote:
> Cortex-A73 (all versions) counter read can return a wrong value
> when the counter crosses a 32bit boundary.
>
> The workaround involves performing the read twice, and to return
> one or the other depending on whether a transition has taken place.

> +#ifdef CONFIG_ARM64_ERRATUM_858921
> +static u64 notrace arm64_858921_read_cntvct_el0(void)
> +{
> + u64 _old, _new;
> +
> + _old = read_sysreg(cntvct_el0);
> + _new = read_sysreg(cntvct_el0);
> + return (((_old ^ _new) >> 32) & 1) ? _old : _new;
> +}
> +#endif

Given this is a static inline, I think we can drop the underscores here.

Thanks,
Mark.