Re: [RFC PATCH 0/5] clockevents: decouple broadcast mechanism fromdrivers

From: Mark Rutland
Date: Wed Jan 02 2013 - 06:41:40 EST

On Fri, Dec 21, 2012 at 10:08:02AM +0000, Santosh Shilimkar wrote:
> Mark,
> On Tuesday 18 December 2012 05:36 PM, Mark Rutland wrote:
> > In some SMP systems, cpu-local timers may stop delivering interrupts
> > when in low power states, or not all CPUs may have local timers. To
> > support these systems we have a mechanism for broadcasting timer ticks
> > to other CPUs. This mechanism relies on the struct
> > clock_event_device::broadcast function pointer, which is a
> > driver-specific mechanism for broadcasting ticks to other CPUs.
> >
> > As the broadcast mechanism is architecture-specific, placing the
> > broadcast function on struct clock_event_device ties each driver to a
> > single architecture. Additionally the driver or architecture backend
> > must handle the routing of broadcast ticks to the correct
> > clock_event_device, leading to duplication of the list of active
> > clock_event_devices.
> >
> > These patches introduce a generic mechanism for handling the receipt of
> > timer broadcasts, and an optional architecture-specific broadcast
> > function which allows drivers to be decoupled from a particular
> > architecture will retaining support for timer tick broadcasts. These
> > mechanisms are wired up for the arm port, and have been boot-tested on a
> > pandaboard.
> >
> Apart from the relevant comments given against couple of patches and
> Stephen's printk string comment, the series looks pretty good to me.
> I have tested the series with CPUIdle where the broadcast is actually
> used actively.


> So feel free to add,
> Reviewed-tested-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>



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