From 22ad8666be5e0edbb77a3b24e926161571d59322 Mon Sep 17 00:00:00 2001
From: Martin Leung <martin.leung@amd.com>
Date: Fri, 19 Feb 2021 18:04:42 -0500
Subject: drm/amd/display: guard for virtual calling destroy_link_encoders
Git-commit: e73b386e75586f28b9b58641938ae0feb340bca0
Patch-mainline: v6.0-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225 jsc#PED-2849

[Why]:
On power down, virtual dal may try to delete link_encoders by
referencing uninitialized res_pool.

[How]:
Added guard against empty res_pool.

Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Martin Leung <martin.leung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/amd/display/dc/core/dc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index 795766cb27dd..34a3e1eeb5c4 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -347,10 +347,16 @@ static bool create_link_encoders(struct dc *dc)
  */
 static void destroy_link_encoders(struct dc *dc)
 {
-	unsigned int num_usb4_dpia = dc->res_pool->res_cap->num_usb4_dpia;
-	unsigned int num_dig_link_enc = dc->res_pool->res_cap->num_dig_link_enc;
+	unsigned int num_usb4_dpia;
+	unsigned int num_dig_link_enc;
 	int i;
 
+	if (!dc->res_pool)
+		return;
+
+	num_usb4_dpia = dc->res_pool->res_cap->num_usb4_dpia;
+	num_dig_link_enc = dc->res_pool->res_cap->num_dig_link_enc;
+
 	/* A platform without USB4 DPIA endpoints has a fixed mapping between DIG
 	 * link encoders and physical display endpoints and does not require
 	 * additional link encoder objects.
-- 
2.38.1