[PATCH 1/5] drm/i915/dp_tunnel: Don't update tunnel state during system resume

[Imre Deak <imre.deak@intel.com>]

During system resume, restoring the pre-suspend display state must not
fail. This requires preserving the sink capabilities from before
suspend, including the available link bandwidth.

If these capabilities are not preserved, the restore modeset may fail,
either due to a missing sink capability or insufficient link bandwidth
for the restored mode.

When the sink is connected through a DP tunnel, prevent such capability
changes by skipping tunnel state updates during resume. This also avoids
updating the sink state via the tunnel while it is being resumed.

Signed-off-by: Imre Deak <imre.deak@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp_tunnel.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_tunnel.c b/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
index faa2b7a46699d..eb1eed1c8c7bb 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_tunnel.c
@@ -150,11 +150,9 @@ static int allocate_initial_tunnel_bw_for_pipes(struct intel_dp *intel_dp, u8 pi
 			    drm_dp_tunnel_name(intel_dp->tunnel),
 			    encoder->base.base.id, encoder->base.name,
 			    ERR_PTR(err));
-
-		return err;
 	}
 
-	return update_tunnel_state(intel_dp);
+	return err;
 }
 
 static int allocate_initial_tunnel_bw(struct intel_dp *intel_dp,
@@ -200,10 +198,13 @@ static int detect_new_tunnel(struct intel_dp *intel_dp, struct drm_modeset_acqui
 	}
 
 	ret = allocate_initial_tunnel_bw(intel_dp, ctx);
-	if (ret < 0)
+	if (ret < 0) {
 		intel_dp_tunnel_destroy(intel_dp);
 
-	return ret;
+		return ret;
+	}
+
+	return update_tunnel_state(intel_dp);
 }
 
 /**
-- 
2.49.1