[PATCH 0/3] Modify the SW tail logic in OA

OA unit updates the HW TAIL register to indicate that a new report is
available, although it does not guarantee that the report is visible in
memory. Also the currently running workload contributes to some latency
in seeing this report in memory. In the past we would set some fields in
the OA report and check if the fields are populated to non-zero values
by the HW, but this is no longer sufficient since some parts of the
report may land out of order under heavy workloads. Drop this WA and add
a new logic that just waits for a fixed number of HW TAIL report
increments before returning data to the user. User will always see the
reports lagging by this fixed number, however we do not have realtime
use cases for OAG since OAG reports are mainly post processed.

v2: Rebase
v3: Add Sashiko's review comments

Signed-off-by: Umesh Nerlige Ramappa <[email protected]>

Umesh Nerlige Ramappa (3):
  drm/xe/xe_oa: Clear status only if relevant bits are set
  drm/xe/xe_oa: Avoid checking and setting fields in the OA report
  drm/xe/xe_oa: Add a lag to the reports that is exported to user

 drivers/gpu/drm/xe/xe_oa.c | 94 +++++---------------------------------
 1 file changed, 12 insertions(+), 82 deletions(-)

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2.51.0