[Intel-gfx] [PATCH] drm/i915: fix RPS on runtime suspend

[Paulo Zanoni]

From: Paulo Zanoni <paulo.r.zanoni at intel.com>

With this patch, the RPS sequence for runtime suspend/resume is
exactly like the sequence for S3 suspend/resume:
 - flush_delayed_work(&dev_priv->rps.delayed_resume_work)
 - intel_runtime_pm_disable_interrupts()
 - intel_suspend_gt_powersave()
   (suspended)
 - intel_runtime_pm_enable_interrupts()
 - intel_enable_gt_powersave()

With this, we get rid of WARNs that are currently intermittently
triggered by the system-suspend-execbuf subtest of runtime PM. Notice
that these WARNs could also be triggered in other ways that involved
doing lots of RPM suspend/resume cycles just after a system S3 resume.

Testcase: igt/pm_rpm/system-suspend-execbuf
Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

Also, with this patch + the sprite planes regression fix, this will be the first
time ever that my BDW machine passes every single test of pm_rpm without any
WARNs! \o/

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 0c7cf48..2404b2b 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1395,13 +1395,9 @@ static int intel_runtime_suspend(struct device *device)
 	i915_gem_release_all_mmaps(dev_priv);
 	mutex_unlock(&dev->struct_mutex);
 
-	/*
-	 * rps.work can't be rearmed here, since we get here only after making
-	 * sure the GPU is idle and the RPS freq is set to the minimum. See
-	 * intel_mark_idle().
-	 */
-	cancel_work_sync(&dev_priv->rps.work);
+	flush_delayed_work(&dev_priv->rps.delayed_resume_work);
 	intel_runtime_pm_disable_interrupts(dev_priv);
+	intel_suspend_gt_powersave(dev);
 
 	ret = intel_suspend_complete(dev_priv);
 	if (ret) {
@@ -1473,7 +1469,7 @@ static int intel_runtime_resume(struct device *device)
 	gen6_update_ring_freq(dev);
 
 	intel_runtime_pm_enable_interrupts(dev_priv);
-	intel_reset_gt_powersave(dev);
+	intel_enable_gt_powersave(dev);
 
 	if (ret)
 		DRM_ERROR("Runtime resume failed, disabling it (%d)\n", ret);
-- 
2.1.1