Messages in this thread | | | Subject | Re: [PATCH] arm: bcm2835: Add the PMU to the devicetree. | From | Florian Fainelli <> | Date | Thu, 17 May 2018 12:59:28 -0700 |
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On 05/17/2018 12:31 PM, Vince Weaver wrote: > On Thu, 17 May 2018, Vince Weaver wrote: > >> On Thu, 17 May 2018, Peter Zijlstra wrote: >> with cortex-a7 now, would it be possible to later drop that if proper >> cortex-a53 support is added to the armv7 pmu driver? Or would that lead >> to all kinds of back-compatability mess? > > For what it's worth, the pi-foundation kernel bcm2710 device tree file > does: > > arm-pmu { > #ifdef RPI364 > compatible = "arm,armv8-pmuv3", "arm,cortex-a7-pmu"; > #else > compatible = "arm,cortex-a7-pmu"; > #endif > interrupt-parent = <&local_intc>; > interrupts = <9>; > }; > > > Which is probably where I was getting the arm,armv8-pmuv3 from in my > original patch.
I thought somehow that Marc Z. had unified arch/arm/kernel/perf_event_v7.c and arch/arm64/kernel/perf_event.c into a common driver entry point under drivers/perf/arm_pmu.c but I don't see it and after about 15 minutes looking at it, it does not look as trivial as I though to separate out those files so the ARMv8 PMU description can be moved into a generic location for instance.
FWIW, Broadcom STB chips, even when 64-bit capable or often used with an 32-bit ARM kernel, so having the ARMv8 PMUs work under a 32-bit ARM kernel would be great. The downstream solution we have sued thus far is to find the closest compatible string to represent those, which is not great... -- Florian
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