Getting zeros on i.MX6 PMU counters using Device Tree Kernel

rathben — Wed, 15 Oct 2014 17:19:16 GMT

I'm having the exact problem that was nicely described in an earlier post regarding pre-DT kernels: Getting zeros on i.MX6 PMU counters

My kernel is 3.10.17. I can "fix" this by somewhat blindly pasting the suggested assembly snippet into the cpu_pmu_device_probe function in arch/arm/kernel/perf_event_cpu.c:

	u32 val = 0b11;
	asm volatile("mcr p15, 0, %0, c1, c1, 1" : : "r" (val));

I'm hoping that there is a more elegant way of doing this. Device tree item perhaps? Has anyone else run into this problem?

Re: Getting zeros on i.MX6 PMU counters using Device Tree Kernel

alejandrolozan1 — Mon, 27 Oct 2014 14:53:55 GMT

Hi,

After checking the problem it seems that the solution shown in the discussion you mentioned.

I doubt there is a solution that can be performed from the DTS, the dts is only for configuration description but I did not find anything for the PMU. I suggest you to stikc with this solution,

Getting zeros on i.MX6 PMU counters

Best Regards,

Alejandro

i.MX ProcessorsのトピックRe: Getting zeros on i.MX6 PMU counters using Device Tree Kernel

Getting zeros on i.MX6 PMU counters using Device Tree Kernel

Re: Getting zeros on i.MX6 PMU counters using Device Tree Kernel