CHROMIUM: i915: Tweak idle timeouts to improve power usage

Reduce the idle timeouts in the i915 driver to improve power usage. By being
slightly more aggresive with the timeouts, we can get the GPU to sleep a bit
faster without significantly increasing the misfires (times when the timer
expires and the stack is still busy).

BUG=chromium-os:9803
TEST=Tried various values, found the times that maximized idling while not
     significantly increasing the missed idles.

Change-Id: Ia0c5835aa0f801b965bc85f8cbc7d15d415c2dac
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/13651
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1b1cf3b..ffaa448 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6992,7 +6992,7 @@ struct drm_display_mode *intel_crtc_mode_get(struct drm_device *dev,
        return mode;
 }
 
-#define GPU_IDLE_TIMEOUT 500 /* ms */
+#define GPU_IDLE_TIMEOUT 400 /* ms */
 
 /* When this timer fires, we've been idle for awhile */
 static void intel_gpu_idle_timer(unsigned long arg)
@@ -7011,7 +7011,7 @@ static void intel_gpu_idle_timer(unsigned long arg)
        queue_work(dev_priv->wq, &dev_priv->idle_work);
 }
 
-#define CRTC_IDLE_TIMEOUT 1000 /* ms */
+#define CRTC_IDLE_TIMEOUT 700 /* ms */
 
 static void intel_crtc_idle_timer(unsigned long arg)
 {