On Tue, Mar 30, 2021 at 04:08:11PM -0500, Rob Herring wrote:

On Tue, Mar 30, 2021 at 12:09 PM Rob Herring [off-list ref] wrote:

quoted

On Tue, Mar 30, 2021 at 10:31 AM Will Deacon [off-list ref] wrote:

quoted

The logic here feels like it
could with a bit of untangling.

Yes, I don't love it, but couldn't come up with anything better. It is
complicated by the fact that flags have to be set before we assign the
counter and can't set/change them when we assign the counter. It would
take a lot of refactoring with armpmu code to fix that.

How's this instead?:

if (armv8pmu_event_want_user_access(event) || !armv8pmu_event_is_64bit(event))
        event->hw.flags |= ARMPMU_EL0_RD_CNTR;

/*
* At this point, the counter is not assigned. If a 64-bit counter is
* requested, we must make sure the h/w has 64-bit counters if we set
* the event size to 64-bit because chaining is not supported with
* userspace access. This may still fail later on if the CPU cycle
* counter is in use.
*/
if (armv8pmu_event_is_64bit(event) &&
    (!armv8pmu_event_want_user_access(event) ||
     armv8pmu_has_long_event(cpu_pmu) || (hw_event_id ==
ARMV8_PMUV3_PERFCTR_CPU_CYCLES)))
        event->hw.flags |= ARMPMU_EVT_64BIT;

I thought there were some cases where we could assign cycles event to an
event counter; does that not happen anymore?

Will

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