From: David Yang <mmyangfl@gmail.com>
Date: Wed, 26 Nov 2025 08:40:19 +0000 (+0800)
Subject: net: dsa: yt921x: Fix parsing MIB attributes
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=510026a39849ae7066dce17343caba4550e2a977;p=thirdparty%2Fkernel%2Flinux.git

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 944988e29127d..97fc6085f4d0b 100644
--- 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);