Messages in this thread | | | Subject | Re: [RFC] Improving udelay/ndelay on platforms where that is possible | From | Marc Gonzalez <> | Date | Thu, 16 Nov 2017 17:51:05 +0100 |
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On 16/11/2017 17:47, Nicolas Pitre wrote:
> Look at cpufreq_callback() in arch/arm/kernel/smp.c.
Are you pointing at the scaling of loops_per_jiffy done in that function?
As I wrote earlier:
If I'm reading arch/arm/kernel/smp.c correctly, loops_per_jiffy is scaled when the frequency changes.
But arch/arm/lib/delay-loop.S starts by loading the current value of loops_per_jiffy, computes the number of times to loop, and then loops. If the frequency increases when the core is in __loop_delay, the delay will be much shorter than requested.
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