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On Thu, Aug 1, 2013 at 6:08 PM, Michael Giardino
<giardino@xxxxxxxxxxxxxx> wrote:
> Hi,
>
> I hope this is the right spot to ask this.
>
> Is there any way to change the cpu frequency using the cpufreq driver
> from within an hrtimer callback function? I encounter a kernel panic
> at cpufreq.c line 255 (260 in 3.9.5)
>
> void __cpufreq_notify_transition(struct cpufreq_policy *policy,
> 253 struct cpufreq_freqs *freqs, unsigned int state)
> 254 {
> 255 BUG_ON(irqs_disabled());
>
>
> I'm assuming this is due to the cpufreq_notify_transition needs
> interrupts to notify? Is there a way around this? It appears that
> acpi-cpufreq.c is calling the notifier both before and after the
> transition (CPUFREQ_PRECHANGE and CPUFREQ_POSTCHANGE).
>
> Are there any frequency change functions that can operate without interrupts?
>
> The background is this:
>
> For the past few days I have been trying to get to the bottom of a
> problem involving a nonSMP governor I have written. The goal of this
> governor is to change the frequency on a predefined schedule (in the
> ms scale). The basic breakdown is this:
>
> 1. The external scheduler computes schedules and then passes them to
> the governor (with much code appropriated from the userspace governor)
> via an exported function.
> 2. The governor sets the frequency, then sets a timer to call the next
> frequency change when it goes off
>
> In order to do this, I was using hrtimers. These timer's callback
> functions run with interrupts disabled.
>
> Michael Giardino
> <giardino@xxxxxxxxxxxxxx>
> <michael.giardino@xxxxxxxxx>
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