[PATCH 5.7 022/179] drm/amd/display: Check DMCU Exists Before Loading

[Greg Kroah-Hartman]

From: Jerry (Fangzhi) Zuo <jerry....@amd.com>

[ Upstream commit 17bdb4a82fe5014c8aa5b2103c80c5729744a096 ]

Signed-off-by: Jerry (Fangzhi) Zuo <jerry....@amd.com>
Reviewed-by: Hersen Wu <hersenxs...@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pil...@amd.com>
Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index d06fa63801799..7da2a22dbde7e 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1342,9 +1342,14 @@ static int dm_late_init(void *handle)
        struct dmcu_iram_parameters params;
        unsigned int linear_lut[16];
        int i;
-       struct dmcu *dmcu = adev->dm.dc->res_pool->dmcu;
+       struct dmcu *dmcu = NULL;
        bool ret;
 
+       if (!adev->dm.fw_dmcu)
+               return detect_mst_link_for_all_connectors(adev->ddev);
+
+       dmcu = adev->dm.dc->res_pool->dmcu;
+
        for (i = 0; i < 16; i++)
                linear_lut[i] = 0xFFFF * i / 15;
 
-- 
2.25.1