drm/radeon/kms: don't try to be smart in the hpd handler

Attempting to try and turn off disconnected display hw in the
hotput handler lead to more problems than it helped.  For
now just register an event and only attempt the do something
interesting with DP.  Other connectors are just too problematic:
- Some systems have an HPD pin assigned to LVDS, but it's rarely
if ever connected properly and we don't really care about hpd
events on LVDS anyway since it's always connected.
- The HPD pin is wired up correctly for eDP, but we don't really
have to do anything since the events since it's always connected.
- Some HPD pins fire more than once when you connect/disconnect
- etc.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=39882

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 645b84b3d20..7ad43c6b1db 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -613,6 +613,18 @@ static bool radeon_dp_get_link_status(struct radeon_connector *radeon_connector,
 	return true;
 }
 
+bool radeon_dp_needs_link_train(struct radeon_connector *radeon_connector)
+{
+	u8 link_status[DP_LINK_STATUS_SIZE];
+	struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
+
+	if (!radeon_dp_get_link_status(radeon_connector, link_status))
+		return false;
+	if (dp_channel_eq_ok(link_status, dig->dp_lane_count))
+		return false;
+	return true;
+}
+
 struct radeon_dp_link_train_info {
 	struct radeon_device *rdev;
 	struct drm_encoder *encoder;