[Intel-gfx] [PATCH] drm/i915: Wait for vblank after register read

[Mika Kahola]

When reading out CRC's we  wait for a vblank on intel_dp_sink_crc_start()
function. When we start reading out CRC's in intel_dp_sink_crc() loop we
first wait for a vblank yielding that all in all we end up waiting two
vblanks on the first iteration round. Therefore, let's move the
intel_wait_for_vblank() as the last routine that we do in an iteration loop
in intel_dp_sink_crc().

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103166
Signed-off-by: Mika Kahola <mika.kahola at intel.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 62f82c4..6eb97fa 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3972,13 +3972,14 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, struct intel_crtc_state *crtc_s
 		return ret;
 
 	do {
-		intel_wait_for_vblank(dev_priv, intel_crtc->pipe);
-
 		if (drm_dp_dpcd_readb(&intel_dp->aux,
 				      DP_TEST_SINK_MISC, &buf) < 0) {
 			ret = -EIO;
 			goto stop;
 		}
+
+		intel_wait_for_vblank(dev_priv, intel_crtc->pipe);
+
 		count = buf & DP_TEST_COUNT_MASK;
 
 	} while (--attempts && count == 0);
-- 
2.7.4