drm/i915: Wait for the struct_mutex on idling

When the system is idling, contention for struct_mutex should be low and
so we will be more efficient to wait for a contended mutex than
reschedule.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190430094405.6127-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_pm.c b/drivers/gpu/drm/i915/i915_gem_pm.c
index 3554d55dae35479f29256ead861176eb054460fa..3b6e8d5be8e1c84a5714973c7e9d9e588fce3c17 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_pm.c
+++ b/drivers/gpu/drm/i915/i915_gem_pm.c
@@ -47,13 +47,7 @@ static void idle_work_handler(struct work_struct *work)
        struct drm_i915_private *i915 =
                container_of(work, typeof(*i915), gem.idle_work.work);
 
-       if (!mutex_trylock(&i915->drm.struct_mutex)) {
-               /* Currently busy, come back later */
-               mod_delayed_work(i915->wq,
-                                &i915->gem.idle_work,
-                                msecs_to_jiffies(50));
-               return;
-       }
+       mutex_lock(&i915->drm.struct_mutex);
 
        intel_wakeref_lock(&i915->gt.wakeref);
        if (!intel_wakeref_active(&i915->gt.wakeref))