[PATCH net-next 2/2] net: stmmac: Tx coe sw fallback

[Rohan G Thomas]

Add sw fallback of tx checksum calculation for those tx queues that
doesn't support  tx checksum offloading. Because, some DWMAC IPs
support tx checksum offloading  only for few initial tx queues,
starting from tx queue 0.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@xxxxxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h  |  2 ++
 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 19 +++++++++++++++++++
 .../ethernet/stmicro/stmmac/stmmac_platform.c |  4 ++++
 include/linux/stmmac.h                        |  1 +
 4 files changed, 26 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 3401e888a9f6..f526bcaaaf64 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -219,6 +219,8 @@ struct stmmac_priv {
 	int hwts_tx_en;
 	bool tx_path_in_lpi_mode;
 	bool tso;
+	bool tx_q_coe_lmt;
+	u32 tx_q_with_coe;
 	int sph;
 	int sph_cap;
 	u32 sarc_type;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index fcab363d8dfa..e095a9bd93b1 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4409,6 +4409,17 @@ 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);
+	/* Some DWMAC IPs support tx coe only for a few initial tx queues,
+	 * starting from tx queue 0. So checksum offloading for those queues
+	 * that doesn't support tx coe need to fallback to software checksum
+	 * calculation.
+	 */
+	if (csum_insertion && priv->tx_q_coe_lmt &&
+	    queue >= priv->tx_q_with_coe) {
+		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);
@@ -7386,6 +7397,14 @@ int stmmac_dvr_probe(struct device *device,
 		dev_info(priv->device, "SPH feature enabled\n");
 	}
 
+	if (priv->plat->tx_coe &&
+	    priv->plat->tx_queues_with_coe < priv->plat->tx_queues_to_use) {
+		priv->tx_q_coe_lmt = true;
+		priv->tx_q_with_coe = priv->plat->tx_queues_with_coe;
+		dev_info(priv->device, "TX COE limited to %u tx queues\n",
+			 priv->tx_q_with_coe);
+	}
+
 	/* Ideally our host DMA address width is the same as for the
 	 * device. However, it may differ and then we have to use our
 	 * host DMA width for allocation and the device DMA width for
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index be8e79c7aa34..0138b7c9c7ab 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -225,6 +225,10 @@ static int stmmac_mtl_setup(struct platform_device *pdev,
 				 &plat->tx_queues_to_use))
 		plat->tx_queues_to_use = 1;
 
+	if (of_property_read_u32(tx_node, "snps,tx-queues-with-coe",
+				 &plat->tx_queues_with_coe))
+		plat->tx_queues_with_coe = plat->tx_queues_to_use;
+
 	if (of_property_read_bool(tx_node, "snps,tx-sched-wrr"))
 		plat->tx_sched_algorithm = MTL_TX_ALGORITHM_WRR;
 	else if (of_property_read_bool(tx_node, "snps,tx-sched-wfq"))
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 652404c03944..795c10d19c1c 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -252,6 +252,7 @@ struct plat_stmmacenet_data {
 	u32 host_dma_width;
 	u32 rx_queues_to_use;
 	u32 tx_queues_to_use;
+	u32 tx_queues_with_coe;
 	u8 rx_sched_algorithm;
 	u8 tx_sched_algorithm;
 	struct stmmac_rxq_cfg rx_queues_cfg[MTL_MAX_RX_QUEUES];
-- 
2.26.2