drm/i915: Align the hangcheck wakeup to the nearest second

round_jiffies() aligns the wakeup time to the nearest second in order to
batch wakeups and reduce system load, which is useful for unimportant
coarse timers like our hangcheck.

v2: round_jiffies_relative() returns the relative jiffie value, whereas
we need the absolute value for the timer.
Suggested-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -452,6 +452,7 @@ typedef struct drm_i915_private {
 
 	/* For hangcheck timer */
 #define DRM_I915_HANGCHECK_PERIOD 1500 /* in ms */
+#define DRM_I915_HANGCHECK_JIFFIES msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD)
 	struct timer_list hangcheck_timer;
 	int hangcheck_count;
 	uint32_t last_acthd[I915_NUM_RINGS];

drivers/gpu/drm/i915/i915_gem.c

@@ -2015,8 +2015,7 @@ i915_add_request(struct intel_ring_buffer *ring,
 	if (!dev_priv->mm.suspended) {
 		if (i915_enable_hangcheck) {
 			mod_timer(&dev_priv->hangcheck_timer,
-				  jiffies +
-				  msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+				  round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
 		}
 		if (was_empty) {
 			queue_delayed_work(dev_priv->wq,

drivers/gpu/drm/i915/i915_irq.c

@@ -353,8 +353,7 @@ static void notify_ring(struct drm_device *dev,
 	if (i915_enable_hangcheck) {
 		dev_priv->hangcheck_count = 0;
 		mod_timer(&dev_priv->hangcheck_timer,
-			  jiffies +
-			  msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+			  round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
 	}
 }
 
@@ -1752,7 +1751,7 @@ void i915_hangcheck_elapsed(unsigned long data)
 repeat:
 	/* Reset timer case chip hangs without another request being added */
 	mod_timer(&dev_priv->hangcheck_timer,
-		  jiffies + msecs_to_jiffies(DRM_I915_HANGCHECK_PERIOD));
+		  round_jiffies_up(jiffies + DRM_I915_HANGCHECK_JIFFIES));
 }
 
 /* drm_dma.h hooks