Ville explained that the wakelock was being acquired during set-idle in order to flush the voltage change from the punit. Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx --- drivers/gpu/drm/i915/intel_pm.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 4406359c5f81..4c9a1b12dfee 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -5011,8 +5011,18 @@ static void vlv_set_rps_idle(struct drm_i915_private *dev_priv) if (dev_priv->rps.cur_freq <= val) return; - /* Wake up the media well, as that takes a lot less - * power than the Render well. */ + /* 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 commiting the voltage change) as that takes a lot less + * power than the render powerwell. + */ intel_uncore_forcewake_get(dev_priv, FORCEWAKE_MEDIA); valleyview_set_rps(dev_priv, val); intel_uncore_forcewake_put(dev_priv, FORCEWAKE_MEDIA); -- 2.11.0 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
