Re: [PATCH v4 4/7] arm_pmu: Tidy up clear_event_idx call backs

From: Suzuki K Poulose
Date: Tue Jul 03 2018 - 09:13:51 EST

On 03/07/18 13:49, Mark Rutland wrote:
On Mon, Jul 02, 2018 at 10:59:45PM +0100, Suzuki K Poulose wrote:
The armpmu uses get_event_idx callback to allocate an event
counter for a given event, which marks the selected counter
as "used". Now, when we delete the counter, the arm_pmu goes
ahead and clears the "used" bit and then invokes the "clear_event_idx"
call back, which kind of splits the job between the core code
and the backend. To keep things tidy, mandate the implementation
of clear_event_idx() and add it for exisiting backends.
This will be useful for adding the chained event support, where
we leave the event idx maintenance to the backend.

Also, when an event is removed from the PMU, reset the hw.idx
to indicate that a counter is not allocated for this event,
to help the backends do better checks. This will be also used
for the chain counter support.

Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Reviewed-by: Julien Thierry <julien.thierry@xxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Changes since v3:
- Add clear_event_idx call back for backends.
arch/arm/kernel/perf_event_v6.c | 8 ++++++++
arch/arm/kernel/perf_event_v7.c | 9 +++++++++
arch/arm64/kernel/perf_event.c | 7 +++++++
drivers/perf/arm_pmu.c | 7 +++----
4 files changed, 27 insertions(+), 4 deletions(-)

I beleive this is missing the xscale PMU code.

Ah! Thanks for spotting. I will fix that.

Otherwiwse, this looks good to me.