[Intel-gfx] [PATCH] drm/i915: Enable runtime pm

[Daniel Vetter]

Like with every other feature that's not enabled by default we break
runtime pm support way too often by accident because the overall test
coverage isn't great. And it's been almost 2 years since we enabled
the power well code by default

commit bf51d5e2cda5d36d98e4b46ac7fca9461e512c41
Author: Paulo Zanoni <paulo.r.zanoni at intel.com>
Date:   Wed Jul 3 17:12:13 2013 -0300

    drm/i915: switch disable_power_well default value to 1

It's really more than overdue for runtime pm itself to follow!

Note that in practice this wont do a hole lot yet, since we're still
gated on snd-hda-intel doing proper runtime pm. But I've discussed
this with Liam and we agreed that this needs to be done. And the audio
team is working to hold up their end of this bargain.

And the justification for updating the autosuspend delay to 100ms:
Quick measurment shows that we can do a full rpm cycle in about 5ms,
which means the delay should still be really conservative from a power
conservation pov. The only workload that would suffer from ping-pong
is also only gpu/compute with all screens off. 100ms should cover any
kind of latency with submitting follow-up batches.

Cc: Takashi Iwai <tiwai at suse.de>
Cc: Liam Girdwood <liam.r.girdwood at intel.com>
Cc: Yang, Libin <libin.yang at intel.com>
Cc: Lin, Mengdong <mengdong.lin at intel.com>
Cc: Li, Jocelyn <jocelyn.li at intel.com>
Cc: Kaskinen, Tanu <tanu.kaskinen at intel.com>
Cc: Zanoni, Paulo R <paulo.r.zanoni at intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 drivers/gpu/drm/i915/intel_runtime_pm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 317b9b43d1c1..36ecbe275dd9 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -1919,9 +1919,10 @@ void intel_runtime_pm_enable(struct drm_i915_private *dev_priv)
 		return;
 	}
 
-	pm_runtime_set_autosuspend_delay(device, 10000); /* 10s */
+	pm_runtime_set_autosuspend_delay(device, 100);
 	pm_runtime_mark_last_busy(device);
 	pm_runtime_use_autosuspend(device);
+	pm_runtime_allow(device);
 
 	pm_runtime_put_autosuspend(device);
 }
-- 
2.1.0