diff options
| author | Chris Wilson <[email protected]> | 2020-12-23 12:23:58 +0000 |
|---|---|---|
| committer | Chris Wilson <[email protected]> | 2020-12-23 21:10:40 +0000 |
| commit | 8391c9b28cbfcf371ce8ebfcf2d62e08a2ea7619 (patch) | |
| tree | 970bc0607d466659f78018d6ee1f0f0cb0025a66 /drivers/gpu/drm/i915/selftests/i915_request.c | |
| parent | 57f62622c3fba5200d8906446825d14b62ba0c07 (diff) | |
drm/i915/selftests: Confirm CS_TIMESTAMP / CTX_TIMESTAMP share a clock
We assume that both timestamps are driven off the same clock [reported
to userspace as I915_PARAM_CS_TIMESTAMP_FREQUENCY]. Verify that this is
so by reading the timestamp registers around a busywait (on an otherwise
idle engine so there should be no preemptions).
v2: Icelake (not ehl, nor tgl) seems to be using a fixed 80ns interval
for, and only for, CTX_TIMESTAMP -- or it may be GPU frequency and the
test is always running at maximum frequency?. As far as I can tell, this
isolated change in behaviour is undocumented.
Signed-off-by: Chris Wilson <[email protected]>
Cc: Mika Kuoppala <[email protected]>
Reviewed-by: Mika Kuoppala <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Diffstat (limited to 'drivers/gpu/drm/i915/selftests/i915_request.c')
0 files changed, 0 insertions, 0 deletions