[Intel-gfx] [PATCH] drm/i915: Remove unecessary per execlist queue item pm reference

[Nick Hoath]

The execlist code was holding a pm reference for the lifetime of an
execlist queue item. Having this pm reference is required when getting
force wakes during execlists_elsp_write. As this happens inside an interrupt
handler and retrieving the reference can sleep, it can't be done more fine
grained. However, the matching execbuffer already holds a pm reference which
covers this timeframe.

Issue: VIZ-4274
Signed-off-by: Nick Hoath <nicholas.hoath at intel.com>
---
 drivers/gpu/drm/i915/intel_lrc.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 1be836a..dc096de 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -297,7 +297,7 @@ static void execlists_elsp_write(struct intel_engine_cs *ring,
 	 *
 	 * The other problem is that we can't just call gen6_gt_force_wake_get()
 	 * because that function calls intel_runtime_pm_get(), which might sleep.
-	 * Instead, we do the runtime_pm_get/put when creating/destroying requests.
+	 * Instead, we rely on the requests pm get/put.
 	 */
 	spin_lock_irqsave(&dev_priv->uncore.lock, flags);
 	if (IS_CHERRYVIEW(dev_priv->dev)) {
@@ -519,8 +519,6 @@ static void execlists_free_request_task(struct work_struct *work)
 	struct drm_device *dev = req->ring->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
-	intel_runtime_pm_put(dev_priv);
-
 	mutex_lock(&dev->struct_mutex);
 	i915_gem_context_unreference(req->ctx);
 	mutex_unlock(&dev->struct_mutex);
@@ -546,8 +544,6 @@ static int execlists_context_queue(struct intel_engine_cs *ring,
 	req->tail = tail;
 	INIT_WORK(&req->work, execlists_free_request_task);
 
-	intel_runtime_pm_get(dev_priv);
-
 	spin_lock_irqsave(&ring->execlist_lock, flags);
 
 	list_for_each_entry(cursor, &ring->execlist_queue, execlist_link)
-- 
2.1.1