drm: Use a nondestructive mode for output detect when polling

Destructive load-detection is very expensive and due to failings
elsewhere can trigger system wide stalls of up to 600ms. A simple
first step to correcting this is not to invoke such an expensive
and destructive load-detection operation automatically.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=29536
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=16265
Reported-by: Bruno Prémont <bonbons@linux-vserver.org>
Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 51d142939a26..e1a2a05fb838 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -1386,7 +1386,8 @@ ironlake_dp_detect(struct drm_connector *connector)
  * \return false if DP port is disconnected.
  */
 static enum drm_connector_status
-intel_dp_detect(struct drm_connector *connector)
+intel_dp_detect(struct drm_connector *connector,
+                bool nondestructive)
 {
         struct drm_encoder *encoder = intel_attached_encoder(connector);
         struct intel_dp *intel_dp = enc_to_intel_dp(encoder);