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drm/i915/gt: Treat idling as a RPS downclock event
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If we park/unpark faster than we can respond to RPS events, we never
will process a downclock event after expiring a waitboost, and thus we
will forever restart the GPU at max clocks even if the workload switches
and doesn't justify full power.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/1500
Fixes: 3e7abf8 ("drm/i915: Extract GT render power state management")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andi Shyti <andi.shyti@intel.com>
Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200322163225.28791-1-chris@chris-wilson.co.uk
Cc: <stable@vger.kernel.org> # v5.5+
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Chris Wilson committed Mar 22, 2020
1 parent bb6892b commit 21abf0b
Showing 1 changed file with 13 additions and 0 deletions.
13 changes: 13 additions & 0 deletions drivers/gpu/drm/i915/gt/intel_rps.c
Original file line number Diff line number Diff line change
Expand Up @@ -771,6 +771,19 @@ void intel_rps_park(struct intel_rps *rps)
intel_uncore_forcewake_get(rps_to_uncore(rps), FORCEWAKE_MEDIA);
rps_set(rps, rps->idle_freq, false);
intel_uncore_forcewake_put(rps_to_uncore(rps), FORCEWAKE_MEDIA);

/*
* Since we will try and restart from the previously requested
* frequency on unparking, treat this idle point as a downclock
* interrupt and reduce the frequency for resume. If we park/unpark
* more frequently than the rps worker can run, we will not respond
* to any EI and never see a change in frequency.
*
* (Note we accommodate Cherryview's limitation of only using an
* even bin by applying it to all.)
*/
rps->cur_freq =
max_t(int, round_down(rps->cur_freq - 1, 2), rps->min_freq);
}

void intel_rps_boost(struct i915_request *rq)
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