drm/i915: Reduce hangcheck frequency

By reducing the hangcheck frequency we check less often, conserving
resources, and still detect a lock up quickly. On a fast machine with a
slow GPU (like a Core2 paired with a 945G) it is easy for the hangcheck to
misfire as we check too fast.

Also once hung and if we fail to completely reset the chip, we have a
nasty habit of proclaming a hang many times a second and generating a
strobe-like display.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e0b7ddc..9391765 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1639,9 +1639,11 @@
 	}
 
 	if (!dev_priv->mm.suspended) {
-		mod_timer(&dev_priv->hangcheck_timer, jiffies + DRM_I915_HANGCHECK_PERIOD);
+		mod_timer(&dev_priv->hangcheck_timer,
+			  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
 		if (was_empty)
-			queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, HZ);
+			queue_delayed_work(dev_priv->wq,
+					   &dev_priv->mm.retire_work, HZ);
 	}
 	return seqno;
 }