2019-09-19 14:43:19 +00:00
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From 26c79197da4b2911e10c600d79839a82a43a06ff Mon Sep 17 00:00:00 2001
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2019-07-09 18:32:28 +00:00
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From: P33M <p33m@github.com>
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Date: Wed, 1 May 2019 17:04:32 +0100
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2019-09-19 14:43:19 +00:00
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Subject: [PATCH 478/806] smsc95xx: dynamically fix up TX buffer alignment with
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2019-07-09 18:32:28 +00:00
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padding bytes
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dwc_otg requires a 32-bit aligned buffer start address, otherwise
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expensive bounce buffers are used. The LAN951x hardware can skip up to
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3 bytes between the TX header and the start of frame data, which can
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be used to force alignment of the URB passed to dwc_otg.
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As found in https://github.com/raspberrypi/linux/issues/2924
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---
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drivers/net/usb/smsc95xx.c | 12 +++++++-----
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drivers/net/usb/smsc95xx.h | 2 +-
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2 files changed, 8 insertions(+), 6 deletions(-)
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--- a/drivers/net/usb/smsc95xx.c
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+++ b/drivers/net/usb/smsc95xx.c
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@@ -2082,7 +2082,9 @@ static struct sk_buff *smsc95xx_tx_fixup
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struct sk_buff *skb, gfp_t flags)
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{
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bool csum = skb->ip_summed == CHECKSUM_PARTIAL;
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- int overhead = csum ? SMSC95XX_TX_OVERHEAD_CSUM : SMSC95XX_TX_OVERHEAD;
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+ unsigned int align_bytes = -((uintptr_t)skb->data) & 0x3;
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+ int overhead = csum ? SMSC95XX_TX_OVERHEAD_CSUM + align_bytes
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+ : SMSC95XX_TX_OVERHEAD + align_bytes;
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u32 tx_cmd_a, tx_cmd_b;
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/* We do not advertise SG, so skbs should be already linearized */
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@@ -2116,16 +2118,16 @@ static struct sk_buff *smsc95xx_tx_fixup
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}
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}
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- skb_push(skb, 4);
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- tx_cmd_b = (u32)(skb->len - 4);
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+ skb_push(skb, 4 + align_bytes);
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+ tx_cmd_b = (u32)(skb->len - 4 - align_bytes);
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if (csum)
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tx_cmd_b |= TX_CMD_B_CSUM_ENABLE;
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cpu_to_le32s(&tx_cmd_b);
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memcpy(skb->data, &tx_cmd_b, 4);
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skb_push(skb, 4);
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- tx_cmd_a = (u32)(skb->len - 8) | TX_CMD_A_FIRST_SEG_ |
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- TX_CMD_A_LAST_SEG_;
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+ tx_cmd_a = (u32)(skb->len - 8 - align_bytes) | TX_CMD_A_FIRST_SEG_ |
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+ (align_bytes << 16) | TX_CMD_A_LAST_SEG_;
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cpu_to_le32s(&tx_cmd_a);
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memcpy(skb->data, &tx_cmd_a, 4);
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--- a/drivers/net/usb/smsc95xx.h
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+++ b/drivers/net/usb/smsc95xx.h
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@@ -21,7 +21,7 @@
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#define _SMSC95XX_H
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/* Tx command words */
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-#define TX_CMD_A_DATA_OFFSET_ (0x001F0000) /* Data Start Offset */
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+#define TX_CMD_A_DATA_OFFSET_ (0x00030000) /* Data Start Offset */
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#define TX_CMD_A_FIRST_SEG_ (0x00002000) /* First Segment */
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#define TX_CMD_A_LAST_SEG_ (0x00001000) /* Last Segment */
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#define TX_CMD_A_BUF_SIZE_ (0x000007FF) /* Buffer Size */
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