[Intel-gfx] [PATCH 02/11] drm/i915: Ignore disconnected Displayport connectors in check_link_status

[Todd Previte]

Adds a check at the top to verify that the device is connected. This is
necessary for DP compliance testing to ensure that test requests are captured
and acknowledged. If a test request is present during a connected->disconnected
transition, the test code will attempt to execute even though the device is
disconnected, resulting in a faied test.

This patch is actually both a bug fix and a component of compliance testing.
Because HPD events are received both on connect and disconnect actions, it's
vital that we don't try and train the link when we're transitioning from
connected->disconnected. That results in errors and warning in the logs from
failed AUX transactions and can trigger the WARN for the check of !base.crtc.
By making the check at the beginning to see if the connection is truly active,
those problems are avoided and testing / link training will only be attempted
when there is a valid Displayport connection.

V1:
- Earlier review feedback recommended the original check_link_status
  patch be split into two. This is the first patch of that split.

Signed-off-by: Todd Previte <tprevite at gmail.com>
---
 drivers/gpu/drm/i915/intel_dp.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index ae0fb98..30cd433 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -3895,21 +3895,13 @@ intel_dp_check_link_status(struct intel_dp *intel_dp)
 
 	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
 
-	if (!intel_encoder->connectors_active)
-		return;
-
-	if (WARN_ON(!intel_encoder->base.crtc))
-		return;
-
-	if (!to_intel_crtc(intel_encoder->base.crtc)->active)
-		return;
-
-	/* Try to read receiver status if the link appears to be up */
-	if (!intel_dp_get_link_status(intel_dp, link_status)) {
+	if (intel_dp->attached_connector->base.status !=
+	    connector_status_connected) {
+		DRM_DEBUG_KMS("Not connected\n");
 		return;
 	}
 
-	/* Now read the DPCD to see if it's actually running */
+	/* Attempt to read the DPCD */
 	if (!intel_dp_get_dpcd(intel_dp)) {
 		return;
 	}
-- 
1.9.1