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From ac011573006f07da4a140f05e1ee8be0c441f3dc Mon Sep 17 00:00:00 2001
From: P33M <p33m@github.com>
Date: Tue, 14 May 2019 14:55:19 +0100
Subject: [PATCH 493/725] Revert "smsc95xx: dynamically fix up TX buffer
 alignment with padding bytes"

As reported in https://github.com/raspberrypi/linux/issues/2964 this
commit causes a regression corrupting non-option TCP ack packets.

This reverts commit 96b972dc736d943f371a16ccca452a053d83c65b.
---
 drivers/net/usb/smsc95xx.c | 12 +++++-------
 drivers/net/usb/smsc95xx.h |  2 +-
 2 files changed, 6 insertions(+), 8 deletions(-)

--- a/drivers/net/usb/smsc95xx.c
+++ b/drivers/net/usb/smsc95xx.c
@@ -2082,9 +2082,7 @@ static struct sk_buff *smsc95xx_tx_fixup
 					 struct sk_buff *skb, gfp_t flags)
 {
 	bool csum = skb->ip_summed == CHECKSUM_PARTIAL;
-	unsigned int align_bytes = -((uintptr_t)skb->data) & 0x3;
-	int overhead = csum ? SMSC95XX_TX_OVERHEAD_CSUM + align_bytes
-				: SMSC95XX_TX_OVERHEAD + align_bytes;
+	int overhead = csum ? SMSC95XX_TX_OVERHEAD_CSUM : SMSC95XX_TX_OVERHEAD;
 	u32 tx_cmd_a, tx_cmd_b;
 
 	/* We do not advertise SG, so skbs should be already linearized */
@@ -2118,16 +2116,16 @@ static struct sk_buff *smsc95xx_tx_fixup
 		}
 	}
 
-	skb_push(skb, 4 + align_bytes);
-	tx_cmd_b = (u32)(skb->len - 4 - align_bytes);
+	skb_push(skb, 4);
+	tx_cmd_b = (u32)(skb->len - 4);
 	if (csum)
 		tx_cmd_b |= TX_CMD_B_CSUM_ENABLE;
 	cpu_to_le32s(&tx_cmd_b);
 	memcpy(skb->data, &tx_cmd_b, 4);
 
 	skb_push(skb, 4);
-	tx_cmd_a = (u32)(skb->len - 8 - align_bytes) | TX_CMD_A_FIRST_SEG_ |
-		(align_bytes << 16) | TX_CMD_A_LAST_SEG_;
+	tx_cmd_a = (u32)(skb->len - 8) | TX_CMD_A_FIRST_SEG_ |
+		TX_CMD_A_LAST_SEG_;
 	cpu_to_le32s(&tx_cmd_a);
 	memcpy(skb->data, &tx_cmd_a, 4);
 
--- a/drivers/net/usb/smsc95xx.h
+++ b/drivers/net/usb/smsc95xx.h
@@ -21,7 +21,7 @@
 #define _SMSC95XX_H
 
 /* Tx command words */
-#define TX_CMD_A_DATA_OFFSET_	(0x00030000)	/* Data Start Offset */
+#define TX_CMD_A_DATA_OFFSET_	(0x001F0000)	/* Data Start Offset */
 #define TX_CMD_A_FIRST_SEG_	(0x00002000)	/* First Segment */
 #define TX_CMD_A_LAST_SEG_	(0x00001000)	/* Last Segment */
 #define TX_CMD_A_BUF_SIZE_	(0x000007FF)	/* Buffer Size */