[PATCH v11 65/65] drm_vblank: use dyndbg's static-key to avoid flag-check

[Jim Cromie]

drm_crtc_vblank_helper_get_vblank_timestamp_internal() is called about
~100 times per sec, on a single display. It currently calls
drm_debug_enabled(DRM_UT_VBL) to avoid doing ktime_to_timespec64()
conversions when the debug logging is disabled.

When CONFIG_DRM_USE_DYNAMIC_DEBUG=Y, the drm_debug_enabled() is
redundant, because the following drm_dbg_vbl() already carries a
static-key optimization.

So move the ktime conversions into the drm_dbg_vbl() argument list,
then they are guarded natively by the static key. This avoids the
double-check entirely.

TBD: if CONFIG_DRM_USE_DYNAMIC_DEBUG=N, this does the ktime
conversions unconditionally, so this might not be prudent (yet).

Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
---
 drivers/gpu/drm/drm_vblank.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index f78bf37f1e0a..0dac7eec2066 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -803,15 +803,11 @@ drm_crtc_vblank_helper_get_vblank_timestamp_internal(
 	 */
 	*vblank_time = ktime_sub_ns(etime, delta_ns);
 
-	if (!drm_debug_enabled(DRM_UT_VBL))
-		return true;
-
-	ts_etime = ktime_to_timespec64(etime);
-	ts_vblank_time = ktime_to_timespec64(*vblank_time);
-
 	drm_dbg_vbl(dev,
 		    "crtc %u : v p(%d,%d)@ %ptSp -> %ptSp [e %d us, %d rep]\n",
-		    pipe, hpos, vpos, &ts_etime, &ts_vblank_time,
+		    pipe, hpos, vpos,
+		    (ts_etime = ktime_to_timespec64(etime), &ts_etime),
+		    (ts_vblank_time = ktime_to_timespec64(*vblank_time), &ts_vblank_time),
 		    duration_ns / 1000, i);
 
 	return true;
-- 
2.53.0