net: dsa: tag_8021q: fix the VLAN IDs used for encoding sub-VLANs

[ Upstream commit 4ef8d857b5f494e62bce9085031563fda35f9563 ]

When using sub-VLANs in the range of 1-7, the resulting value from:

	rx_vid = dsa_8021q_rx_vid_subvlan(ds, port, subvlan);

is wrong according to the description from tag_8021q.c:

 | 11  | 10  |  9  |  8  |  7  |  6  |  5  |  4  |  3  |  2  |  1  |  0  |
 +-----------+-----+-----------------+-----------+-----------------------+
 |    DIR    | SVL |    SWITCH_ID    |  SUBVLAN  |          PORT         |
 +-----------+-----+-----------------+-----------+-----------------------+

For example, when ds->index == 0, port == 3 and subvlan == 1,
dsa_8021q_rx_vid_subvlan() returns 1027, same as it returns for
subvlan == 0, but it should have returned 1043.

This is because the low portion of the subvlan bits are not masked
properly when writing into the 12-bit VLAN value. They are masked into
bits 4:3, but they should be masked into bits 5:4.

Fixes: 3eaae1d05f2b ("net: dsa: tag_8021q: support up to 8 VLANs per port using sub-VLANs")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/dsa/tag_8021q.c b/net/dsa/tag_8021q.c
index 8e3e8a5b855930b3aa20d5251ff66e235562f0c8..a00b513c22a1db108b69054d3cc8a99d307dc3bc 100644 (file)
--- a/net/dsa/tag_8021q.c
+++ b/net/dsa/tag_8021q.c
@@ -64,7 +64,7 @@
 #define DSA_8021Q_SUBVLAN_HI_SHIFT     9
 #define DSA_8021Q_SUBVLAN_HI_MASK      GENMASK(9, 9)
 #define DSA_8021Q_SUBVLAN_LO_SHIFT     4
-#define DSA_8021Q_SUBVLAN_LO_MASK      GENMASK(4, 3)
+#define DSA_8021Q_SUBVLAN_LO_MASK      GENMASK(5, 4)
 #define DSA_8021Q_SUBVLAN_HI(x)                (((x) & GENMASK(2, 2)) >> 2)
 #define DSA_8021Q_SUBVLAN_LO(x)                ((x) & GENMASK(1, 0))
 #define DSA_8021Q_SUBVLAN(x)           \