r8169: confusion between hardware and IP header alignment

The rx copybreak part is straightforward.

The align field in struct rtl_cfg_info is related to the alignment
requirements of the DMA operation. Its value is set at 2 to limit the
scale of possible regression but my old v1.21 8169 datasheet claims a
8 bytes requirements (which never appeared in the driver, of course)
and the 8101/8168 go with a plain 8 bytes alignment.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Edward Hsu <edward_hsu@realtek.com.tw>

1 files changed, 5 insertions, 7 deletions

diff --git a/drivers/net/r8169.c b/drivers/net/r8169.c
index 9c49d910c06d..a6fea192ffff 100644
--- a/drivers/net/r8169.c
+++ b/drivers/net/r8169.c
@@ -1490,7 +1490,7 @@ static const struct rtl_cfg_info {
         [RTL_CFG_0] = {
                 .hw_start       = rtl_hw_start_8169,
                 .region         = 1,
-                .align          = NET_IP_ALIGN,
+                .align          = 2,
                 .intr_event     = SYSErr | LinkChg | RxOverflow |
                                   RxFIFOOver | TxErr | TxOK | RxOK | RxErr,
                 .napi_event     = RxFIFOOver | TxErr | TxOK | RxOK | RxOverflow
@@ -2649,8 +2649,7 @@ static inline void rtl8169_rx_csum(struct sk_buff *skb, struct RxDesc *desc)
 }
 
 static inline bool rtl8169_try_rx_copy(struct sk_buff **sk_buff, int pkt_size,
-                                       struct pci_dev *pdev, dma_addr_t addr,
-                                       unsigned int align)
+                                       struct pci_dev *pdev, dma_addr_t addr)
 {
         struct sk_buff *skb;
         bool done = false;
@@ -2658,12 +2657,12 @@ static inline bool rtl8169_try_rx_copy(struct sk_buff **sk_buff, int pkt_size,
         if (pkt_size >= rx_copybreak)
                 goto out;
 
-        skb = dev_alloc_skb(pkt_size + align);
+        skb = dev_alloc_skb(pkt_size + NET_IP_ALIGN);
         if (!skb)
                 goto out;
 
         pci_dma_sync_single_for_cpu(pdev, addr, pkt_size, PCI_DMA_FROMDEVICE);
-        skb_reserve(skb, (align - 1) & (unsigned long)skb->data);
+        skb_reserve(skb, NET_IP_ALIGN);
         skb_copy_from_linear_data(*sk_buff, skb->data, pkt_size);
         *sk_buff = skb;
         done = true;
@@ -2732,8 +2731,7 @@ rtl8169_rx_interrupt(struct net_device *dev, struct rtl8169_private *tp,
 
                         rtl8169_rx_csum(skb, desc);
 
-                        if (rtl8169_try_rx_copy(&skb, pkt_size, pdev, addr,
-                                                tp->align)) {
+                        if (rtl8169_try_rx_copy(&skb, pkt_size, pdev, addr)) {
                                 pci_dma_sync_single_for_device(pdev, addr,
                                         pkt_size, PCI_DMA_FROMDEVICE);
                                 rtl8169_mark_to_asic(desc, tp->rx_buf_sz);