[U-Boot] [PATCH] lib: time: Add microsecond timer

[Marek Vasut]

On 10/16/19 6:54 PM, Simon Glass wrote:
> Hi Marek,

Hello Simon,

> On Wed, 16 Oct 2019 at 10:44, Marek Vasut wrote:
>>
>> On 10/16/19 6:40 PM, Simon Glass wrote:
>>> Hi Marek,
>>
>> Hi,
>>
>>> On Wed, 16 Oct 2019 at 02:55, Marek Vasut wrote:
>>>>
>>>> On 10/16/19 3:30 AM, Simon Glass wrote:
>>>>> Hi Marek,
>>>>
>>>> Hi,
>>>>
>>>>> On Tue, 15 Oct 2019 at 14:43, Marek Vasut wrote:
>>>>>>
>>>>>> Add get_timer_us(), which is useful e.g. when we need higher
>>>>>> precision timestamps.
>>>>>
>>>>> Can we use timer_get_us()? It seems confusing to have two.
>>>>
>>>> Nope, that one doesn't have the range (unsigned long vs. u64) and also
>>>> doesn't behave the same way as old get_timer(). I wanted something which
>>>> is similar, just for uS instead of mS.
>>>
>>> Can you add comments to your patch to indicate what is going on any
>>> why to use this?
>>>
>>> Bootstage uses ulong which is enough for about an hour. How long is
>>> U-Boot running?
>>
>> It can run as long as anyone needs.
>>
>>> If you are using differential times, presumably for timeouts, then
>>> there seems to be little reason to need u64.
>>
>> I use it for logging timestamps during profiling, e.g. of the EHCI driver.
> 
> Have you tried bootstage?

What for ? I need to debug the EHCI driver performance across the EHCI
driver and USB storage implementation. Bootstage is not helpful here.

-- 
Best regards,
Marek Vasut