lantiq: xrx200: replace patch with upstream version

This commit replaces patch number 0703 with the upstream accepted
version. This patch requires backporting an additional patch to
avoid conflicts.

The only significant change is the lower maximum MTU. Packets with
lengths over 2400 may be dropped.

Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
(cherry picked from commit b4970dab6b0c3e13715f4b13de42d72a74c1c9e9)

1 files changed, 104 insertions, 0 deletions

diff --git a/target/linux/lantiq/patches-5.10/0704-v5.17-net-lantiq_xrx200-add-ingress-SG-DMA-support.patch b/target/linux/lantiq/patches-5.10/0704-v5.17-net-lantiq_xrx200-add-ingress-SG-DMA-support.patch
new file mode 100644
index 0000000000..f2c36952fc
--- /dev/null
+++ b/target/linux/lantiq/patches-5.10/0704-v5.17-net-lantiq_xrx200-add-ingress-SG-DMA-support.patch
@@ -0,0 +1,104 @@
+From c3e6b2c35b34214c58c1e90d65dab5f5393608e7 Mon Sep 17 00:00:00 2001
+From: Aleksander Jan Bajkowski <olek2@wp.pl>
+Date: Mon, 3 Jan 2022 20:43:16 +0100
+Subject: [PATCH] net: lantiq_xrx200: add ingress SG DMA support
+
+This patch adds support for scatter gather DMA. DMA in PMAC splits
+the packet into several buffers when the MTU on the CPU port is
+less than the MTU of the switch. The first buffer starts at an
+offset of NET_IP_ALIGN. In subsequent buffers, dma ignores the
+offset. Thanks to this patch, the user can still connect to the
+device in such a situation. For normal configurations, the patch
+has no effect on performance.
+
+Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ drivers/net/ethernet/lantiq_xrx200.c | 47 +++++++++++++++++++++++-----
+ 1 file changed, 40 insertions(+), 7 deletions(-)
+
+--- a/drivers/net/ethernet/lantiq_xrx200.c
++++ b/drivers/net/ethernet/lantiq_xrx200.c
+@@ -26,6 +26,9 @@
+ #define XRX200_DMA_RX		0
+ #define XRX200_DMA_TX		1
+ 
++#define XRX200_DMA_PACKET_COMPLETE	0
++#define XRX200_DMA_PACKET_IN_PROGRESS	1
++
+ /* cpu port mac */
+ #define PMAC_RX_IPG		0x0024
+ #define PMAC_RX_IPG_MASK	0xf
+@@ -61,6 +64,9 @@ struct xrx200_chan {
+ 	struct ltq_dma_channel dma;
+ 	struct sk_buff *skb[LTQ_DESC_NUM];
+ 
++	struct sk_buff *skb_head;
++	struct sk_buff *skb_tail;
++
+ 	struct xrx200_priv *priv;
+ };
+ 
+@@ -204,7 +210,8 @@ static int xrx200_hw_receive(struct xrx2
+ 	struct xrx200_priv *priv = ch->priv;
+ 	struct ltq_dma_desc *desc = &ch->dma.desc_base[ch->dma.desc];
+ 	struct sk_buff *skb = ch->skb[ch->dma.desc];
+-	int len = (desc->ctl & LTQ_DMA_SIZE_MASK);
++	u32 ctl = desc->ctl;
++	int len = (ctl & LTQ_DMA_SIZE_MASK);
+ 	struct net_device *net_dev = priv->net_dev;
+ 	int ret;
+ 
+@@ -220,12 +227,36 @@ static int xrx200_hw_receive(struct xrx2
+ 	}
+ 
+ 	skb_put(skb, len);
+-	skb->protocol = eth_type_trans(skb, net_dev);
+-	netif_receive_skb(skb);
+-	net_dev->stats.rx_packets++;
+-	net_dev->stats.rx_bytes += len;
+ 
+-	return 0;
++	/* add buffers to skb via skb->frag_list */
++	if (ctl & LTQ_DMA_SOP) {
++		ch->skb_head = skb;
++		ch->skb_tail = skb;
++	} else if (ch->skb_head) {
++		if (ch->skb_head == ch->skb_tail)
++			skb_shinfo(ch->skb_tail)->frag_list = skb;
++		else
++			ch->skb_tail->next = skb;
++		ch->skb_tail = skb;
++		skb_reserve(ch->skb_tail, -NET_IP_ALIGN);
++		ch->skb_head->len += skb->len;
++		ch->skb_head->data_len += skb->len;
++		ch->skb_head->truesize += skb->truesize;
++	}
++
++	if (ctl & LTQ_DMA_EOP) {
++		ch->skb_head->protocol = eth_type_trans(ch->skb_head, net_dev);
++		netif_receive_skb(ch->skb_head);
++		net_dev->stats.rx_packets++;
++		net_dev->stats.rx_bytes += ch->skb_head->len;
++		ch->skb_head = NULL;
++		ch->skb_tail = NULL;
++		ret = XRX200_DMA_PACKET_COMPLETE;
++	} else {
++		ret = XRX200_DMA_PACKET_IN_PROGRESS;
++	}
++
++	return ret;
+ }
+ 
+ static int xrx200_poll_rx(struct napi_struct *napi, int budget)
+@@ -240,7 +271,9 @@ static int xrx200_poll_rx(struct napi_st
+ 
+ 		if ((desc->ctl & (LTQ_DMA_OWN | LTQ_DMA_C)) == LTQ_DMA_C) {
+ 			ret = xrx200_hw_receive(ch);
+-			if (ret)
++			if (ret == XRX200_DMA_PACKET_IN_PROGRESS)
++				continue;
++			if (ret != XRX200_DMA_PACKET_COMPLETE)
+ 				return ret;
+ 			rx++;
+ 		} else {