bcm63xx: sync ethernet driver with net-next

Sync ethernet driver code with upstream Linux kernel:
-Reduce xmit_more code changes.
-Combine rx cleanup code into a function.
-Convert to build_skb.
-Improve rx loop by optimizing loop tracking.

https://lore.kernel.org/netdev/20210106144208.1935-1-liew.s.piaw@gmail.com/
Signed-off-by: Sieng Piaw Liew <liew.s.piaw@gmail.com>
[Amend commit description, move patches to the top since they are going to be
upstreamed]
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/target/linux/bcm63xx/patches-5.4/046-v5.12-bcm63xx_enet-improve-rx-loop.patch b/target/linux/bcm63xx/patches-5.4/046-v5.12-bcm63xx_enet-improve-rx-loop.patch
new file mode 100644
index 0000000000..65d3e2571a
--- /dev/null
+++ b/target/linux/bcm63xx/patches-5.4/046-v5.12-bcm63xx_enet-improve-rx-loop.patch
@@ -0,0 +1,40 @@
+From ae2259eebeacb7753e3043278957b45840123972 Mon Sep 17 00:00:00 2001
+From: Sieng Piaw Liew <liew.s.piaw@gmail.com>
+Date: Wed, 6 Jan 2021 22:42:08 +0800
+Subject: [PATCH 7/7] bcm63xx_enet: improve rx loop
+
+Use existing rx processed count to track against budget, thereby making
+budget decrement operation redundant.
+
+rx_desc_count can be calculated outside the rx loop, making the loop a
+bit smaller.
+
+Signed-off-by: Sieng Piaw Liew <liew.s.piaw@gmail.com>
+Acked-by: Florian Fainelli <f.fainelli@gmail.com>
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+---
+ drivers/net/ethernet/broadcom/bcm63xx_enet.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/drivers/net/ethernet/broadcom/bcm63xx_enet.c
++++ b/drivers/net/ethernet/broadcom/bcm63xx_enet.c
+@@ -340,7 +340,6 @@ static int bcm_enet_receive_queue(struct
+ 		priv->rx_curr_desc++;
+ 		if (priv->rx_curr_desc == priv->rx_ring_size)
+ 			priv->rx_curr_desc = 0;
+-		priv->rx_desc_count--;
+ 
+ 		/* if the packet does not have start of packet _and_
+ 		 * end of packet flag set, then just recycle it */
+@@ -405,9 +404,10 @@ static int bcm_enet_receive_queue(struct
+ 		dev->stats.rx_bytes += len;
+ 		list_add_tail(&skb->list, &rx_list);
+ 
+-	} while (--budget > 0);
++	} while (processed < budget);
+ 
+ 	netif_receive_skb_list(&rx_list);
++	priv->rx_desc_count -= processed;
+ 
+ 	if (processed || !priv->rx_desc_count) {
+ 		bcm_enet_refill_rx(dev, true);