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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2020-12-23 15:23:58 +0300 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2020-12-24 00:10:40 +0300 |
| commit | 8391c9b28cbfcf371ce8ebfcf2d62e08a2ea7619 (patch) | |
| tree | 970bc0607d466659f78018d6ee1f0f0cb0025a66 /scripts/gcc-plugins/cyc_complexity_plugin.c | |
| parent | 57f62622c3fba5200d8906446825d14b62ba0c07 (diff) | |
| download | linux-8391c9b28cbfcf371ce8ebfcf2d62e08a2ea7619.tar.xz | |
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 <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201223122359.22562-1-chris@chris-wilson.co.uk
Diffstat (limited to 'scripts/gcc-plugins/cyc_complexity_plugin.c')
0 files changed, 0 insertions, 0 deletions