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, 2 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index de152a58967d..fb6b70fc6572 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -103,7 +103,7 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
                 if (connector->funcs->force)
                         connector->funcs->force(connector);
         } else {
-                connector->status = connector->funcs->detect(connector);
+                connector->status = connector->funcs->detect(connector, false);
                 drm_kms_helper_poll_enable(dev);
         }
 
@@ -866,7 +866,7 @@ static void output_poll_execute(struct work_struct *work)
                     !(connector->polled & DRM_CONNECTOR_POLL_HPD))
                         continue;
 
-                status = connector->funcs->detect(connector);
+                status = connector->funcs->detect(connector, true);
                 if (old_status != status)
                         changed = true;
         }