From f9b4c681de3b822d8c037f7ec92afdbb06f369a3 Mon Sep 17 00:00:00 2001
From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Date: Tue, 5 Nov 2019 12:51:51 -0500
Subject: drm/amd/display: Spin for DMCUB PHY init in DC
Git-commit: a6e4da40bda5682072f1b26b19ce3d25a1b43bf7
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

[Why]
DCN will hang if we access registers before PHY init is done.

So we need to spin or abort.

[How]
On hardware with DMCUB running and working we shouldn't time out
waiting for this to finish and we shouldn't hit the spin cycle.

If there's no hardware support then we should exit out of the function
early assuming that PHY init was already done elsewhere.

If we hit the timeout then there's likely a bug in firmware or software
and we need to debug - add errors and asserts as appropriate.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c | 21 ++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
index 8d348a5f5599..59c298a6484f 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
+++ b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
@@ -112,10 +112,23 @@ void dc_dmub_srv_wait_phy_init(struct dc_dmub_srv *dc_dmub_srv)
 	struct dc_context *dc_ctx = dc_dmub_srv->ctx;
 	enum dmub_status status;
 
-	status = dmub_srv_wait_for_phy_init(dmub, 10000000);
-	if (status != DMUB_STATUS_OK) {
-		DC_ERROR("Error waiting for DMUB phy init: status=%d\n",
-			 status);
+	for (;;) {
+		/* Wait up to a second for PHY init. */
+		status = dmub_srv_wait_for_phy_init(dmub, 1000000);
+		if (status == DMUB_STATUS_OK)
+			/* Initialization OK */
+			break;
+
+		DC_ERROR("DMCUB PHY init failed: status=%d\n", status);
 		ASSERT(0);
+
+		if (status != DMUB_STATUS_TIMEOUT)
+			/*
+			 * Server likely initialized or we don't have
+			 * DMCUB HW support - this won't end.
+			 */
+			break;
+
+		/* Continue spinning so we don't hang the ASIC. */
 	}
 }
-- 
2.28.0