Exception "Could not sample hardware counters." thrown for Mali-T760 MP8 about hwcpipe

[abbaswasim]

Just to confirm are you running the following?

adb shell setprop security.perf_harden 0

[reubenscratton]

No am not doing that, we've never needed to do it - our code & hwcpipe works fine on all other devices, as far as I know. (We don't use CPU counters, only GPU, so no Meltdown/Spectre considerations). I'll try it to see if it makes a difference though.

[reubenscratton]

Just tried it, it made no difference.

[abbaswasim]

Ok thanks for confirming. Sorry Not very helpful then. @solidpixel any thoughts.

[bengaineyarm]

Most likely this is because these few devices are quite old and predate the first Mali driver version that supported reading h/w counters via the public ioctl interface. IIRC this is Mali driver version m_r12, so if you are able to detect the driver version (which should be of the form r<n>p<n> (such as r12p0) this will help identify whether the driver is too old or not.

[reubenscratton]

Do 'r' and 'p' correspond to MaliHWInfo::r_value and MaliHWInfo::p_value as found in vendor/arm/mali/mali_profiler.cpp ?

[bengaineyarm]

IIRC, no, those r/p values refer to the revision of the hardware (so will likely read as something like r1p0).

You might try (from adb shell): cat /sys/module/mali_kbase/version which on an S8 gives r22p0-01rel0 (UK version 11.5)

[solidpixel]

For the Samsung devices, we only support Galaxy S7 onwards.

Galaxy S6 will not work because the counters are not exposed due to a device manufacturer customization of the kernel driver.

I doubt we ever tested a Galaxy S5 - it predates HWCPipe, and is very likely on the older kernel IOCTL we don't support.

[solidpixel]

We should add a section on "supported devices/driver versions" to the project readme.txt.