[PATCH 09/25] coresight: perf: Improve hardware state transitions

[James Clark]

On 15/09/2026 16:48, Leo Yan wrote:
> Keep hw.state consistent with event activation and AUX buffer updates.
> Initialize events as stopped and up to date, clear both flags after a
> successful start, and set UPTODATE after committing an AUX buffer
> update. On resume, clear UPTODATE only on success. Preserve state on
> resume failure and ignore duplicate stops.
> 
> Add helpers for setting and clearing state bits. Use READ_ONCE() and
> WRITE_ONCE() to prevent compiler merging or refetching of state
> accesses.
> 
> Assisted-by: Codex:gpt-6
> Signed-off-by: Leo Yan <leo.yan at arm.com>
> ---
>   drivers/hwtracing/coresight/coresight-etm-perf.c | 58 ++++++++++++++++--------
>   1 file changed, 40 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> index e3c9d3cf84c502f357a430bc3bfa854a776618f1..f66c99b26e1862ab04105704276c901b21728207 100644
> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> @@ -150,6 +150,20 @@ etm_event_cpu_path(struct etm_event_data *data, int cpu)
>   	return *etm_event_cpu_path_ptr(data, cpu);
>   }
>   
> +static inline void etm_event_set_hw_state(struct perf_event *event, int mask)

Extremely minor nit, but inline does nothing here.