drm/i915/crt: Do not rely upon the HPD presence pin

Whilst most monitors do wire up the HPD presence pin, it seems quite a
few KVM do not. Therefore if we simply rely on the HPD pin being
asserted to indicate a connected monitor we fail miserable, so fall back
to performing a DCC query for the EDID.

Reported-and-tested-by: Matthieu LAVIE <boiteamadmax@hotmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=50501
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 75a70c4..844e93e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -453,13 +453,15 @@ intel_crt_detect(struct drm_connector *connector, bool force)
        struct intel_load_detect_pipe tmp;
 
        if (I915_HAS_HOTPLUG(dev)) {
+               /* We can not rely on the HPD pin always being correctly wired
+                * up, for example many KVM do not pass it through, and so
+                * only trust an assertion that the monitor is connected.
+                */
                if (intel_crt_detect_hotplug(connector)) {
                        DRM_DEBUG_KMS("CRT detected via hotplug\n");
                        return connector_status_connected;
-               } else {
+               } else
                        DRM_DEBUG_KMS("CRT not detected via hotplug\n");
-                       return connector_status_disconnected;
-               }
        }
 
        if (intel_crt_detect_ddc(connector))