On Mon, Dec 19, 2016 at 09:47:37AM -0800, Olof Johansson wrote:
> This is useful to get an indication of how much time we spent in firmware.
>
> It's not guaranteed that the timer started at 0 on reset, so it's just
> an approximation, and might very well be invalid on some systems. But
> it's still a useful metric to have access to.
Hi Olof,
[ ... ]
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -521,6 +521,8 @@ arch_timer_detect_rate(void __iomem *cntbase, struct
> device_node *np)
>
> static void arch_timer_banner(unsigned type)
> {
> + unsigned long cnt = arch_timer_read_counter();
> +
arch_timer_banner() is called before arch_counter_register() where the
arch_timer_read_counter() function pointer is set.
Perhaps the arch_timer_banner() and arch_counter_register() should be swapped in
arch_timer_common_init().
> pr_info("Architected %s%s%s timer(s) running at %lu.%02luMHz
> (%s%s%s).\n",
> type & ARCH_CP15_TIMER ? "cp15" : "",
> type == (ARCH_CP15_TIMER | ARCH_MEM_TIMER) ? " and " : "",
> @@ -534,6 +536,8 @@ static void arch_timer_banner(unsigned type)
> type & ARCH_MEM_TIMER ?
> arch_timer_mem_use_virtual ? "virt" : "phys" :
> "");
> + pr_info("Initial timer value: 0x%lx: %ld.%02lds\n",
> + cnt, cnt/arch_timer_rate, (cnt/(arch_timer_rate/100)) % 100);
> }
>
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