On 2019-09-27 13:36, Benjamin GAIGNARD wrote:
On 9/27/19 1:22 PM, Marc Zyngier wrote:
On 2019-09-27 09:48, Benjamin Gaignard wrote:
Adding always-on makes arm arch_timer claim to be an high
resolution
timer.
That is possible because power mode won't stop clocking the timer.
The "always-on" is not about the clock. It is about the comparator.
The clock itself is *guaranteed* to always tick. If it didn't,
that'd be
an integration bug, and a pretty bad one.
What you're claiming here is that your CPU never enters a low-power
mode?
Ever? I find this very hard to believe.
Furthermore, claiming that always-on is the way to force the
arch-timer
to be an hrtimer is factually wrong. This is what happens *if* this
is
the only timer in the system. The only case this is true is for
virtual
machines. Anything else has a global timer somewhere that will allow
the arch timers to be used as an hrtimer.
I'm pretty sure you too have a global timer somewhere in your
system.
Enable it, and enjoy hrtimers without having to lie about the
properties
of your system! ;-)
Hi Marc,
This SoC doesn't have any other global timer. Use arch_time is the
only
we have to provide hrtimer on this system.
And you don't have any form of power management either? What happens
when
your CPU goes into idle? If your system does any form of power
management
*and* doesn't have a separate timer, it is remarkably broken.
M.
--
Jazz is not dead. It just smells funny...
