Messages in this thread | | | Date | Tue, 15 Jan 2013 08:48:21 +0000 | From | Lee Jones <> | Subject | Re: [PATCH 04/18] power: ab8500_fg: Replace msleep() with usleep_range() for greater accuracy |
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On Mon, 14 Jan 2013, Joe Perches wrote:
> On Fri, 2013-01-11 at 13:12 +0000, Lee Jones wrote: > > Doing so provides a greater degree of accuracy when dealing with > > time-frames between 1us and 20ms. msleep() is only accurate for > > wake-ups greater than 20ms. > [] > > diff --git a/drivers/power/ab8500_fg.c b/drivers/power/ab8500_fg.c > [] > > @@ -956,7 +956,7 @@ static int ab8500_fg_load_comp_volt_to_capacity(struct ab8500_fg *di) > > do { > > vbat += ab8500_fg_bat_voltage(di); > > i++; > > - msleep(5); > > + usleep_range(5000, 5001); > > If you're going to give a range that small > you might as well use usleep instead. > > Otherwise, add some tolerance to allow any > other coalesced wakeup to occur.
I can't increase the tolerance, as I don't know how that would effect the running of the system, and the person who would know is off on parental leave.
What I can tell you is we're only using usleep_range() because there is no usleep in the kernel. At least that's what we've been led to believe:
Documentation/timers/timers-howto.txt:
- Why is there no "usleep" / What is a good range? Since usleep_range is built on top of hrtimers, the wakeup will be very precise (ish), thus a simple usleep function would likely introduce a large number of undesired interrupts.
-- Lee Jones Linaro ST-Ericsson Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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