Re: [PATCH v3] clocksource: Add driver for the Ingenic JZ47xx OST

[Thomas Gleixner]

Paul Cercueil <paul@xxxxxxxxxxxxxxx> writes:
> Le mer., janv. 15, 2020 at 20:54, Thomas Gleixner <tglx@xxxxxxxxxxxxx> 
>> That lock still a massive contention point as clock readouts can be 
>> pretty
>> frequent depending on workloads. Just think about tracing ...
>> 
>> So I really would avoid both the lock and that ugly 64bit readout 
>> thing.
>
> The 64bit readout thing is gone in V3.
>
> The lock cannot go away unless we have a way to retrieve the underlying 
> mmio pointer from the regmap, which the regmap maintainers will never 
> accept. So I can't really change that now. Besides, 
> drivers/clocksource/ingenic-timer.c also registers a clocksource that's 
> read with the regmap, and nobody complained.

I don't complain. I just told you that a spinlock in that code path is
really suboptimal.

I missed the one in the other driver, but the same problem exists there.

Thanks,

        tglx