We can compute system time corresponding to GPU timestamp by taking a
reference point (CPU monotonic time, GPU timestamp) and then adding
delta time computed using timecounter/cyclecounter support in kernel.
We have to configure cyclecounter with the GPU timestamp frequency.
Earlier approach that was based on cross-timestamp is not needed. It
was being used to approximate the frequency based on invalid assumptions
(possibly drift was being seen in the time due to precision issue).
The precision of time from GPU clocks is already in ns and timecounter
takes care of it as verified over variable durations.
This series adds base timecounter/cyclecounter changes and changes to
get GPU and CPU timestamps in OA samples.
Sagar Arun Kamble (1):
drm/i915/perf: Add support to correlate GPU timestamp with system time
Sourab Gupta (3):
drm/i915/perf: Add support for collecting 64 bit timestamps with OA
reports
drm/i915/perf: Extract raw GPU timestamps from OA reports
drm/i915/perf: Send system clock monotonic time in perf samples
drivers/gpu/drm/i915/i915_drv.h | 11 ++++
drivers/gpu/drm/i915/i915_perf.c | 124 ++++++++++++++++++++++++++++++++++++++-
drivers/gpu/drm/i915/i915_reg.h | 6 ++
include/uapi/drm/i915_drm.h | 14 +++++
4 files changed, 154 insertions(+), 1 deletion(-)
--
1.9.1
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