In the selftest, we are observing that requests to change frequency are
simply not occuring [within a 20ms period]. The assumption was that with
an active GPU, these writes would be flush naturally; this appears to be
false.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
drivers/gpu/drm/i915/gt/intel_rps.c | 33 ++++++++++++++---------------
1 file changed, 16 insertions(+), 17 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_rps.c
b/drivers/gpu/drm/i915/gt/intel_rps.c
index 4dcfae16a7ce..3c68358040dd 100644
--- a/drivers/gpu/drm/i915/gt/intel_rps.c
+++ b/drivers/gpu/drm/i915/gt/intel_rps.c
@@ -698,18 +698,32 @@ static int rps_set(struct intel_rps *rps, u8 val, bool
update)
if (val == rps->last_freq)
return 0;
+ /*
+ * The punit delays the write of the frequency and voltage until it
+ * determines the GPU is awake. During normal usage we don't want to
+ * waste power changing the frequency if the GPU is sleeping (rc6).
+ * However, the GPU and driver is now idle and we do not want to delay
+ * switching to minimum voltage (reducing power whilst idle) as we do
+ * not expect to be woken in the near future and so must flush the
+ * change by waking the device.
+ */
+ intel_uncore_forcewake_get(rps_to_uncore(rps), FORCEWAKE_ALL);
+
if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
err = vlv_rps_set(rps, val);
else
err = gen6_rps_set(rps, val);
if (err)
- return err;
+ goto out_fw;
if (update)
gen6_rps_set_thresholds(rps, val);
+
rps->last_freq = val;
- return 0;
+out_fw:
+ intel_uncore_forcewake_put(rps_to_uncore(rps), FORCEWAKE_ALL);
+ return err;
}
void intel_rps_unpark(struct intel_rps *rps)
@@ -755,22 +769,7 @@ void intel_rps_park(struct intel_rps *rps)
if (rps->last_freq <= rps->idle_freq)
return;
- /*
- * The punit delays the write of the frequency and voltage until it
- * determines the GPU is awake. During normal usage we don't want to
- * waste power changing the frequency if the GPU is sleeping (rc6).
- * However, the GPU and driver is now idle and we do not want to delay
- * switching to minimum voltage (reducing power whilst idle) as we do
- * not expect to be woken in the near future and so must flush the
- * change by waking the device.
- *
- * We choose to take the media powerwell (either would do to trick the
- * punit into committing the voltage change) as that takes a lot less
- * power than the render powerwell.
- */
- 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
--
2.20.1
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