| Date | Tue, 23 Jul 2013 11:23:34 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH v2 1/3] drivers: clocksource: configure event stream for ARM arch timer |
| |
On Mon, Jul 22, 2013 at 12:21:20PM +0100, Sudeep KarkadaNagesha wrote: > From: Will Deacon <will.deacon@arm.com> > > The ARM architected timer can generate events (used for waking up > CPUs executing the wfe instruction) at a frequency represented as a > power-of-2 divisor of the clock rate. > > This patch configures the event stream, aiming for a period of 100us > between events. This can be used to implement wfe-based timeouts for > userspace locking implementations. ... > --- a/include/clocksource/arm_arch_timer.h > +++ b/include/clocksource/arm_arch_timer.h > @@ -29,6 +29,8 @@ > #define ARCH_TIMER_PHYS_ACCESS 0 > #define ARCH_TIMER_VIRT_ACCESS 1 > > +#define ARCH_TIMER_EVT_STREAM_FREQ 10000 /* 100us */
BTW, if user-space starts using this, it will become an ABI. Is this the right frequency?
In addition, do we want to expose this via hwcap? Something like HWCAP_EVSTR100US?
-- Catalin
|