Patch "net: stmmac: Tx coe sw fallback" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: stmmac: Tx coe sw fallback

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-stmmac-tx-coe-sw-fallback.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 071be3267bf1cf00cff09a9e6758055b060f2a7b
Author: Rohan G Thomas <rohan.g.thomas@xxxxxxxxx>
Date:   Sat Sep 16 14:33:12 2023 +0800

    net: stmmac: Tx coe sw fallback
    
    [ Upstream commit 8452a05b2c633b708dbe3e742f71b24bf21fe42d ]
    
    Add sw fallback of tx checksum calculation for those tx queues that
    don't support tx checksum offloading. DW xGMAC IP can be synthesized
    such that it can support tx checksum offloading only for a few
    initial tx queues. Also as Serge pointed out, for the DW QoS IP, tx
    coe can be individually configured for each tx queue.
    
    So when tx coe is enabled, for any tx queue that doesn't support
    tx coe with 'coe-unsupported' flag set will have a sw fallback
    happen in the driver for tx checksum calculation when any packets to
    be transmitted on these tx queues.
    
    Signed-off-by: Rohan G Thomas <rohan.g.thomas@xxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Stable-dep-of: c2945c435c99 ("net: stmmac: Prevent DSA tags from breaking COE")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 1bfcf673b3ce..59e07efe08c9 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4417,6 +4417,16 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	WARN_ON(tx_q->tx_skbuff[first_entry]);
 
 	csum_insertion = (skb->ip_summed == CHECKSUM_PARTIAL);
+	/* DWMAC IPs can be synthesized to support tx coe only for a few tx
+	 * queues. In that case, checksum offloading for those queues that don't
+	 * support tx coe needs to fallback to software checksum calculation.
+	 */
+	if (csum_insertion &&
+	    priv->plat->tx_queues_cfg[queue].coe_unsupported) {
+		if (unlikely(skb_checksum_help(skb)))
+			goto dma_map_err;
+		csum_insertion = !csum_insertion;
+	}
 
 	if (likely(priv->extend_desc))
 		desc = (struct dma_desc *)(tx_q->dma_etx + entry);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 2f0678f15fb7..30d5e635190e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -276,6 +276,9 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
 			plat->tx_queues_cfg[queue].use_prio = true;
 		}
 
+		plat->tx_queues_cfg[queue].coe_unsupported =
+			of_property_read_bool(q_node, "snps,coe-unsupported");
+
 		queue++;
 	}
 	if (queue != plat->tx_queues_to_use) {
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index e3f7ee169c08..5acb77968902 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -139,6 +139,7 @@ struct stmmac_rxq_cfg {
 
 struct stmmac_txq_cfg {
 	u32 weight;
+	bool coe_unsupported;
 	u8 mode_to_use;
 	/* Credit Base Shaper parameters */
 	u32 send_slope;