[Intel-gfx] [PATCH v2 1/2] drm/i915: Unbind objects in shrinker only if device is runtime active

[Praveen Paneri]

When the system is running low on memory, gem shrinker is invoked.
In this process objects will be unbounded from GTT and unbinding process
will require access to GTT(GTTADR) and also to fence register potentially.
That requires a resume of gfx device, if suspended, in the shrinker path.
Considering the power leakage due to intermediate resume, perform unbinding
operation only if device is already runtime active.

v2: Using newly implemented intel_runtime_pm_get_if_in_use()

Signed-off-by: Akash Goel <akash.goel at intel.com>
Signed-off-by: Praveen Paneri <praveen.paneri at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem_shrinker.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index d3c473f..3bc292d 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -129,6 +129,15 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
 	i915_gem_retire_requests(dev_priv->dev);
 
 	/*
+	 * Unbinding of objects will require HW access; Let us not wake the
+	 * device just to recover a little memory. If absolutely necessary,
+	 * we will force the wake during oom-notifier.
+	 */
+	if ((flags & I915_SHRINK_BOUND) &&
+	    !intel_runtime_pm_get_if_in_use(dev_priv))
+		flags &= ~I915_SHRINK_BOUND;
+
+	/*
 	 * As we may completely rewrite the (un)bound list whilst unbinding
 	 * (due to retiring requests) we have to strictly process only
 	 * one element of the list at the time, and recheck the list
@@ -188,6 +197,9 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
 		list_splice(&still_in_list, phase->list);
 	}
 
+	if (flags & I915_SHRINK_BOUND)
+		intel_runtime_pm_put(dev_priv);
+
 	i915_gem_retire_requests(dev_priv->dev);
 
 	return count;
-- 
1.9.1