drm/amdgpu: handle asics with 1 SDMA instance

This patch will handle asics with 1 SDMA instance.
Signed-off-by: Xiaojian Du <Xiaojian.Du@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/soc21.c

@@ -252,8 +252,9 @@ static int soc21_read_register(struct amdgpu_device *adev, u32 se_num,
 	*value = 0;
 	for (i = 0; i < ARRAY_SIZE(soc21_allowed_read_registers); i++) {
 		en = &soc21_allowed_read_registers[i];
-		if (reg_offset !=
-		    (adev->reg_offset[en->hwip][en->inst][en->seg] + en->reg_offset))
+		if ((i == 7 && (adev->sdma.num_instances == 1)) || /* some asics don't have SDMA1 */
+			reg_offset !=
+			(adev->reg_offset[en->hwip][en->inst][en->seg] + en->reg_offset))
 			continue;
 
 		*value = soc21_get_register_value(adev,