On Wed, Jan 13, 2016 at 11:36:26PM -0500, George G. Davis wrote: > From: Martin Fuzzey <mfuzzey@xxxxxxxxxxx> > > ARMv7 counters other than the CPU cycle counter only work if the Secure > Debug Enable Register (SDER) SUNIDEN bit is set. > > Since access to the SDER is only possible in secure state, it will > only be done if the device tree property "secure-reg-access" is set. > > Without this: > # perf stat -e cycles,instructions sleep 1 > > Performance counter stats for 'sleep 1': > > 14606094 cycles # 0.000 GHz > 0 instructions # 0.00 insns per cycle > > After applying: > # perf stat -e cycles,instructions sleep 1 > > Performance counter stats for 'sleep 1': > > 5843809 cycles > 2566484 instructions # 0.44 insns per cycle > > 1.020144000 seconds time elapsed > > Some platforms (eg i.MX53) may also need additional platform specific > setup. > > Signed-off-by: Martin Fuzzey <mfuzzey@xxxxxxxxxxx> > Signed-off-by: Pooya Keshavarzi <Pooya.Keshavarzi@xxxxxxxxxxxx> > Signed-off-by: George G. Davis <george_davis@xxxxxxxxxx> > --- > Changes in v4: > - Reword commit message to clarify that this change is ARMv7 specific. > - Clarify that secure-reg-access property is only valid for ARMv7 CPUs > and is not supported on anything else (in particular, the arm64 > port requires you to boot in non-secure mode). > - Convert on_each_cpu(armv7pmu_enable_secure_access, NULL, 1) call in > armv7pmu_init() to in-lined code in ->reset callback, since that is > called off the back of a CPU hotplug notifier when the PMU may need > to be reinitialised. Thanks. I'll queue this for 4.6 along with Rob's ack. Will -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
