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/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index c9f3cc5949a8..5536223fbac8 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -386,7 +386,8 @@ struct drm_connector_funcs {
         void (*dpms)(struct drm_connector *connector, int mode);
         void (*save)(struct drm_connector *connector);
         void (*restore)(struct drm_connector *connector);
-        enum drm_connector_status (*detect)(struct drm_connector *connector);
+        enum drm_connector_status (*detect)(struct drm_connector *connector,
+                                            bool nondestructive);
         int (*fill_modes)(struct drm_connector *connector, uint32_t max_width, uint32_t max_height);
         int (*set_property)(struct drm_connector *connector, struct drm_property *property,
                              uint64_t val);