[PATCH v2 0/3] coresight: Fix for snapshot mode

[Leo Yan]

This patch series is to correct the pointer usages for the snapshot
mode.

Patch 01 is to polish code, it removes the redundant header maintained
in tmc-etr driver and directly uses pointer perf_output_handle::head.

Patch 02 removes the callback cs_etm_find_snapshot() which wrongly
calculates the buffer headers; we can simply use the perf's common
function __auxtrace_mmap__read() for headers calculation.  Patch 03 is
to update comments in CoreSight drivers to reflect the changes
introduced by patch 02.

This patch can be cleanly applied on the mainline kernel with:

  commit dbe69e433722 ("Merge tag 'net-next-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next")

And it has been tested on Arm64 Juno board.

Changes from v1:
- Dropped the patch "coresight: etm-perf: Correct buffer syncing for
  snapshot", after a long discussion, the patch doesn't really resolve
  any issues for snapshot mode.  And another reason for unlike this
  patch is now the CoreSight and Intel-PT have the consistent behaviour
  (Suzuki/James/Mathieu);
- Added the patch 03 to updates drivers' comments (James);
- Added Suzuki's review tag for patch 01;
- Added James' review and testing tags for patch 02.


Leo Yan (3):
  coresight: tmc-etr: Use perf_output_handle::head for AUX ring buffer
  perf cs-etm: Remove callback cs_etm_find_snapshot()
  coresight: Update comments for removing cs_etm_find_snapshot()

 drivers/hwtracing/coresight/coresight-etb10.c |   2 +-
 .../hwtracing/coresight/coresight-tmc-etf.c   |   2 +-
 .../hwtracing/coresight/coresight-tmc-etr.c   |  12 +-
 tools/perf/arch/arm/util/cs-etm.c             | 133 ------------------
 4 files changed, 6 insertions(+), 143 deletions(-)

-- 
2.25.1