Do some cleanups then add a new format attribute to set the timestamp interval for ETMv4 in Perf mode. The current interval is too high for most use cases, and particularly on the FVP the number of timestamps generated is excessive.
Although it would be good to make only SYNC timestamps the default and have counter timestamps opt-in, this would be a breaking change. We can always do that later, or disable counter timestamps from Perf.
This is added as an event format attribute, rather than a Coresight config because it's something that the driver is already configuring automatically in Perf mode with any unused counter, so it's not possible to modify this with a config.
Applies to coresight/next
Signed-off-by: James Clark james.clark@linaro.org --- Changes in v2: - Only show the attribute for ETMv4 to improve usability and fix the arm32 build error. Wrapping everything in IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM4X) isn't ideal, but the -perf.c file is shared between ETMv3 and ETMv4, and there is already precedent for doing it this way. - Link to v1: https://lore.kernel.org/r/20250811-james-cs-syncfreq-v1-0-b001cd6e3404@linar...
--- James Clark (6): coresight: Change syncfreq to be a u8 coresight: Fix holes in struct etmv4_config coresight: Repack struct etmv4_drvdata coresight: Refactor etm4_config_timestamp_event() coresight: Add format attribute for setting the timestamp interval coresight: docs: Document etm4x ts_interval
Documentation/trace/coresight/coresight.rst | 14 +++ drivers/hwtracing/coresight/coresight-etm-perf.c | 13 ++- drivers/hwtracing/coresight/coresight-etm4x-core.c | 110 +++++++++++++-------- drivers/hwtracing/coresight/coresight-etm4x.h | 86 ++++++++++------ 4 files changed, 151 insertions(+), 72 deletions(-) --- base-commit: a80198ba650f50d266d7fc4a6c5262df9970f9f2 change-id: 20250724-james-cs-syncfreq-7c2257a38ed3
Best regards,