[dts][PATCH V1] vf_vlan: modify code to adapt dcf vlan offload

[Zhimin Huang <zhiminx.huang@intel.com>]

After sync with dev,change rx path is not safe on device.
Usually the device driver requires the device not be started to change offloads.
For now the test result under vector path is normal.
So we change to scalar path to test dcf vlan offload.

Signed-off-by: Zhimin Huang <zhiminx.huang@intel.com>
---
 test_plans/vf_vlan_test_plan.rst | 7 ++++++-
 tests/TestSuite_vf_vlan.py       | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/test_plans/vf_vlan_test_plan.rst b/test_plans/vf_vlan_test_plan.rst
index 0cf946d0..d1bd69fd 100644
--- a/test_plans/vf_vlan_test_plan.rst
+++ b/test_plans/vf_vlan_test_plan.rst
@@ -80,11 +80,16 @@ if test DCF, set VF port to dcf and start up::
 
        ip link set $PF_INTF vf 0 trust on
 
-    dpdk-testpmd -c 0x0f -n 4 -a 00:04.0,cap=dcf -a 00:05.0,cap=dcf -- -i --portmask=0x3
+   start testpmd with scalar path:
+
+    dpdk-testpmd -c 0x0f -n 4 -a 00:04.0,cap=dcf -a 00:05.0,cap=dcf --force-max-simd-bitwidth=64 -- -i --portmask=0x3
 
 .. note::
 
    make dcf as full feature pmd is dpdk22.07 feature, and only support E810 series nic.
+   the dcf not support vlan offload and change the rx path in vector path when pmd is initialized, so we use
+   the scalar path to start testpmd(use param "--force-max-simd-bitwidth=64").
+
 
 Test Case 1: Add port based vlan on VF
 ======================================
diff --git a/tests/TestSuite_vf_vlan.py b/tests/TestSuite_vf_vlan.py
index 563d06b6..7e4d49df 100644
--- a/tests/TestSuite_vf_vlan.py
+++ b/tests/TestSuite_vf_vlan.py
@@ -169,11 +169,13 @@ class TestVfVlan(TestCase):
     def launch_testpmd(self, **kwargs):
         dcf_flag = kwargs.get("dcf_flag")
         param = kwargs.get("param") if kwargs.get("param") else ""
+        # for dcf mode, the vlan offload support in scalar path
         if dcf_flag:
             self.vm0_testpmd.start_testpmd(
                 VM_CORES_MASK,
                 ports=[self.vf0_guest_pci, self.vf1_guest_pci],
                 param=param,
+                eal_param="--force-max-simd-bitwidth=64",
                 port_options={
                     self.vf0_guest_pci: "cap=dcf",
                     self.vf1_guest_pci: "cap=dcf",
-- 
2.17.1