[U-Boot] [PATCH 04/20] tegra: Provide more accurate microsecond time

[Simon Glass]

Hi Stephen,

On 25 February 2015 at 16:10, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 02/17/2015 03:29 PM, Simon Glass wrote:
>>
>> Add an implementation of the timer functions for tegra, so that timing
>> is more accurate. Tegra has a 1 microsecond timer for this purpose.
>
>
> I'm a bit confused about this:
>
> include/configs/tegra-common.h:32:#define CONFIG_SYS_TIMER_COUNTER
> NV_PA_TMRUS_BASE
>
> lib/time.c:
>
> #ifdef CONFIG_SYS_TIMER_COUNTER
> unsigned long notrace timer_read_counter(void)
> {
> #ifdef CONFIG_SYS_TIMER_COUNTS_DOWN
>         return ~readl(CONFIG_SYS_TIMER_COUNTER);
> #else
>         return readl(CONFIG_SYS_TIMER_COUNTER);
> #endif
> }
>
> Doesn't that provide the same set of features, without requiring
> Tegra-specific code?

Yes you are right. I couldn't find out where this was being done and
was seeing strange behaviour with udelay(). I'm not very keen on the
lldiv() in lib/time.c when it is a no-op. But I suppose all it can do
is slow things down a bit.

Anyway, we can drop this patch.

Regards,
Simon