[PATCH] drm/amd/display: Look at firmware version to determine using dmub on dcn21

[Mario Limonciello]

commit b1c61212d8dc ("drm/amd/display: Fully switch to dmub for all dcn21
asics") switched over to using dmub on Renoir to fix Gitlab 1735, but this
implied a new dependency on newer firmware which might not be met on older
kernel versions.

Since sw_init runs before hw_init, there is an opportunity to determine
whether or not the firmware version is new to adjust the behavior.

Cc: Roman.Li at amd.com
BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1772
BugLink: https://gitlab.freedesktop.org/drm/amd/-/issues/1735
Fixes: b1c61212d8dc ("drm/amd/display: Fully switch to dmub for all dcn21 asics")
Signed-off-by: Mario Limonciello <mario.limonciello at amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 2 +-
 1 file changed, 1 insertion(+), 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 6dd6262f2769..85b3de97f870 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1410,7 +1410,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 		switch (adev->ip_versions[DCE_HWIP][0]) {
 		case IP_VERSION(2, 1, 0):
 			init_data.flags.gpu_vm_support = true;
-			init_data.flags.disable_dmcu = true;
+			init_data.flags.disable_dmcu = adev->dm.dmcub_fw_version > 0x01000000;
 			break;
 		case IP_VERSION(1, 0, 0):
 		case IP_VERSION(1, 0, 1):
-- 
2.25.1