[Intel-gfx] [PATCH v2 7/9] drm/i915/rpm: Enable D3Cold VRAM SR Support

[Anshuman Gupta]

Intel Client DGFX card supports D3Cold with two option.
D3Cold-off zero watt, D3Cold-VRAM Self Refresh.

i915 requires to evict the lmem objects to smem in order to
support D3Cold-Off, which increases i915 the suspend/resume
latency. Enabling VRAM Self Refresh feature optimize the
latency with additional power cost which required to retain
the lmem.

Adding intel_runtime_idle (runtime_idle callback) to enable
VRAM_SR, it will be used for policy to choose
between D3Cold-off vs D3Cold-VRAM_SR.

Since we have introduced i915 runtime_idle callback.
It need to be warranted that Runtime PM Core invokes runtime_idle
callback when runtime usages count becomes zero. That requires
to use pm_runtime_put instead of pm_runtime_put_autosuspend.

TODO: GuC interface state save/restore.

Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Chris Wilson <chris.p.wilson at intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
---
 drivers/gpu/drm/i915/i915_driver.c      | 26 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_runtime_pm.c |  3 +--
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
index aa1fb15b1f11..fcff5f3fe05e 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -1557,6 +1557,31 @@ static int i915_pm_restore(struct device *kdev)
 	return i915_pm_resume(kdev);
 }
 
+static int intel_runtime_idle(struct device *kdev)
+{
+	struct drm_i915_private *dev_priv = kdev_to_i915(kdev);
+	int ret = 1;
+
+	if (!HAS_LMEM_SR(dev_priv)) {
+		/*TODO: Prepare for D3Cold-Off */
+		goto out;
+	}
+
+	disable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
+
+	ret = intel_pm_vram_sr(dev_priv, true);
+	if (!ret)
+		drm_dbg(&dev_priv->drm, "VRAM Self Refresh enabled\n");
+
+	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
+
+out:
+	pm_runtime_mark_last_busy(kdev);
+	pm_runtime_autosuspend(kdev);
+
+	return ret;
+}
+
 static int intel_runtime_suspend(struct device *kdev)
 {
 	struct drm_i915_private *dev_priv = kdev_to_i915(kdev);
@@ -1742,6 +1767,7 @@ const struct dev_pm_ops i915_pm_ops = {
 	.restore = i915_pm_restore,
 
 	/* S0ix (via runtime suspend) event handlers */
+	.runtime_idle = intel_runtime_idle,
 	.runtime_suspend = intel_runtime_suspend,
 	.runtime_resume = intel_runtime_resume,
 };
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 6ed5786bcd29..4dade7e8a795 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -492,8 +492,7 @@ static void __intel_runtime_pm_put(struct intel_runtime_pm *rpm,
 
 	intel_runtime_pm_release(rpm, wakelock);
 
-	pm_runtime_mark_last_busy(kdev);
-	pm_runtime_put_autosuspend(kdev);
+	pm_runtime_put(kdev);
 }
 
 /**
-- 
2.26.2