drm/amd/display: Reset DMCUB before HW init

[Why]
If the firmware wasn't reset by PSP or HW and is currently running
then the firmware will hang or perform underfined behavior when we
modify its firmware state underneath it.

[How]
Reset DMCUB before setting up cache windows and performing HW init.

Reviewed-by: Aurabindo Jayamohanan Pillai <[email protected]>
Acked-by: Pavle Kotarac <[email protected]>
Tested-by: Daniel Wheeler <[email protected]>
Signed-off-by: Nicholas Kazlauskas <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: Nicholas Kazlauskas

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -1051,6 +1051,11 @@ static int dm_dmub_hw_init(struct amdgpu_device *adev)
 		return 0;
 	}
 
+	/* Reset DMCUB if it was previously running - before we overwrite its memory. */
+	status = dmub_srv_hw_reset(dmub_srv);
+	if (status != DMUB_STATUS_OK)
+		DRM_WARN("Error resetting DMUB HW: %d\n", status);
+
 	hdr = (const struct dmcub_firmware_header_v1_0 *)dmub_fw->data;
 
 	fw_inst_const = dmub_fw->data +