net: dsa: yt921x: Fix parsing MIB attributes

There are hard-to-find unused fields in the MIB table I didn't notice in
the example driver code, causing wrong interpretation of the MIB data.

For some 64-bit attributes, the current (wrong) implementation took the
correct lower 32 bits, but messed up the upper 32 bits, so it would work
accidentally until 32-bit overflows happen. Fix that too.

Fixes: 186623f4aa72 ("net: dsa: yt921x: Add support for Motorcomm YT921x")
Signed-off-by: David Yang <mmyangfl@gmail.com>
Link: https://patch.msgid.link/20251126084024.2843851-2-mmyangfl@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/dsa/yt921x.c b/drivers/net/dsa/yt921x.c
index 944988e29127d9d1d58fa0390c488f40c1f98968..97fc6085f4d0b8a28b3ff97dc1893f65df9cf669 100644 (file)
--- a/drivers/net/dsa/yt921x.c
+++ b/drivers/net/dsa/yt921x.c
@@ -56,13 +56,13 @@ static const struct yt921x_mib_desc yt921x_mib_descs[] = {
 
        MIB_DESC(1, 0x30, NULL),        /* RxPktSz1024To1518 */
        MIB_DESC(1, 0x34, NULL),        /* RxPktSz1519ToMax */
-       MIB_DESC(2, 0x38, NULL),        /* RxGoodBytes */
-       /* 0x3c */
+       /* 0x38 unused */
+       MIB_DESC(2, 0x3c, NULL),        /* RxGoodBytes */
 
-       MIB_DESC(2, 0x40, "RxBadBytes"),
-       /* 0x44 */
-       MIB_DESC(2, 0x48, NULL),        /* RxOverSzErr */
-       /* 0x4c */
+       /* 0x40 */
+       MIB_DESC(2, 0x44, "RxBadBytes"),
+       /* 0x48 */
+       MIB_DESC(1, 0x4c, NULL),        /* RxOverSzErr */
 
        MIB_DESC(1, 0x50, NULL),        /* RxDropped */
        MIB_DESC(1, 0x54, NULL),        /* TxBroadcast */
@@ -79,10 +79,10 @@ static const struct yt921x_mib_desc yt921x_mib_descs[] = {
        MIB_DESC(1, 0x78, NULL),        /* TxPktSz1024To1518 */
        MIB_DESC(1, 0x7c, NULL),        /* TxPktSz1519ToMax */
 
-       MIB_DESC(2, 0x80, NULL),        /* TxGoodBytes */
-       /* 0x84 */
-       MIB_DESC(2, 0x88, NULL),        /* TxCollision */
-       /* 0x8c */
+       /* 0x80 unused */
+       MIB_DESC(2, 0x84, NULL),        /* TxGoodBytes */
+       /* 0x88 */
+       MIB_DESC(1, 0x8c, NULL),        /* TxCollision */
 
        MIB_DESC(1, 0x90, NULL),        /* TxExcessiveCollistion */
        MIB_DESC(1, 0x94, NULL),        /* TxMultipleCollision */
@@ -705,7 +705,7 @@ static int yt921x_read_mib(struct yt921x_priv *priv, int port)
                        res = yt921x_reg_read(priv, reg + 4, &val1);
                        if (res)
                                break;
-                       val = ((u64)val0 << 32) | val1;
+                       val = ((u64)val1 << 32) | val0;
                }
 
                WRITE_ONCE(*valp, val);