net: stmmac: vlan: Drop redundant mac_device_info::hw_vlan_en flaggmac/ext1/vlan

The flag has been introduced in the commit 750011e239a5 ("net: stmmac: Add
support for HW-accelerated VLAN stripping") in order to logically split up
the HW-offloaded VLAN tag stripping and the stripping implemented in the
driver. As the commit log says it's supposed to be in sync with the
NETIF_F_HW_VLAN_CTAG_RX feature-flag, otherwise the software-based VLAN
tag stripping will be performed.

First of all the denoted semantics is incorrect, since the MAC and
driver-based VLAN tag stripping are mutually exclusive features and are
supposed to be enabled/disabled by the
NETIF_F_HW_VLAN_CTAG_RX/NETIF_F_HW_VLAN_STAG_RX feature flags. Secondly
the flags can be directly retrieved from the net_device::features field
anytime in the driver. So introducing another mirror-flag for that was
unnecessary. Finally the MAC-based VLAN tag stripping is always persistent
in the DW *MAC IP-cores supporting VLANs (at least DW Ether QoS and DW
XGMAC). Thus as long as the HW-offloaded VLAN tag stripping is implemented
in the respective VLAN driver it can be utilized instead of the
software-based tag stripping code.

So to speak let's drop the mac_device_info::hw_vlan_en flag and just
switch on/off the VLAN tags stripping feature based on the respective
flags set in the net_device::features field. Please note that since the
VLAN-based features are available on the kernel with the CONFIG_VLAN_8021Q
config enabled it is pointless to parse VLAN Ethernet-header if the config
is disable. In that case the entire stmmac_get_rx_vlan() body can be
compiled off thus speeding up the Rx fast-path of the driver.

Note as a nice side effect of this change the VLAN tag stripping feature
is now capable to be switched on/off by the system administrator
irrespective whether it's HW-offloaded or not.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>

4 files changed, 40 insertions, 27 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/common.h b/drivers/net/ethernet/stmicro/stmmac/common.h
index 8403a3e17211..dff7a12047a2 100644
--- a/drivers/net/ethernet/stmicro/stmmac/common.h
+++ b/drivers/net/ethernet/stmicro/stmmac/common.h
@@ -661,7 +661,6 @@ struct mac_device_info {
 	u32 vlan_filter[32];
 	bool vlan_fail_q_en;
 	u8 vlan_fail_q;
-	bool hw_vlan_en;
 	bool reverse_sgmii_enable;
 
 	/* This spinlock protects read-modify-write of the interrupt
diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.h b/drivers/net/ethernet/stmicro/stmmac/hwif.h
index 45111ec4902f..6996fe2e1336 100644
--- a/drivers/net/ethernet/stmicro/stmmac/hwif.h
+++ b/drivers/net/ethernet/stmicro/stmmac/hwif.h
@@ -632,7 +632,8 @@ struct stmmac_vlan_ops {
 				 bool is_svlan);
 	void (*rx_hw_vlan)(struct mac_device_info *hw, struct dma_desc *rx_desc,
 			   struct sk_buff *skb);
-	void (*set_hw_vlan_mode)(struct mac_device_info *hw, bool tx_stag);
+	void (*set_hw_vlan_mode)(struct mac_device_info *hw, bool rx_strip,
+				 bool tx_stag);
 	int (*add_hw_vlan_rx_fltr)(struct net_device *dev,
 				   struct mac_device_info *hw,
 				   __be16 proto, u16 vid);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index ae2dea6b3d3c..47de06bbde2f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -3893,6 +3893,8 @@ static int stmmac_hw_setup(struct net_device *dev)
 
 	phylink_rx_clk_stop_block(priv->phylink);
 	stmmac_set_hw_vlan_mode(priv, priv->hw,
+				dev->features & (NETIF_F_HW_VLAN_CTAG_RX |
+						 NETIF_F_HW_VLAN_STAG_RX),
 				dev->features & NETIF_F_HW_VLAN_STAG_TX);
 	phylink_rx_clk_stop_unblock(priv->phylink);
 
@@ -5158,22 +5160,43 @@ static int stmmac_get_rx_status(struct stmmac_priv *priv, struct dma_desc *p)
 	return ret | discard_frame;
 }
 
-static void stmmac_rx_vlan(struct net_device *dev, struct sk_buff *skb)
+/**
+ * stmmac_get_rx_vlan - Extract VLAN ID from the frame
+ * @priv: driver private structure
+ * @p   : descriptor pointer
+ * @skb : the socket buffer
+ * Description :
+ * This function will either read the VLAN ID and TCI from the DMA-descriptor
+ * (if it's supported the VLAN stripping has been enabled) or just perform
+ * the VLAN header stripping directly from the payload.
+ */
+static void stmmac_get_rx_vlan(struct stmmac_priv *priv, struct dma_desc *p,
+			       struct sk_buff *skb)
 {
+#ifdef STMMAC_VLAN_TAG_USED
 	struct vlan_ethhdr *veth = skb_vlan_eth_hdr(skb);
-	__be16 vlan_proto = veth->h_vlan_proto;
+	__be16 vlan_proto;
 	u16 vlanid;
+	int ret;
+
+	/* MAC level stripping */
+	ret = stmmac_rx_hw_vlan(priv, priv->hw, p, skb);
+	if (!ret)
+		return;
 
+	/* Driver level stripping */
+	vlan_proto = veth->h_vlan_proto;
 	if ((vlan_proto == htons(ETH_P_8021Q) &&
-	     dev->features & NETIF_F_HW_VLAN_CTAG_RX) ||
+	     priv->dev->features & NETIF_F_HW_VLAN_CTAG_RX) ||
 	    (vlan_proto == htons(ETH_P_8021AD) &&
-	     dev->features & NETIF_F_HW_VLAN_STAG_RX)) {
+	     priv->dev->features & NETIF_F_HW_VLAN_STAG_RX)) {
 		/* pop the vlan tag */
 		vlanid = ntohs(veth->h_vlan_TCI);
 		memmove(skb->data + VLAN_HLEN, veth, ETH_ALEN * 2);
 		skb_pull(skb, VLAN_HLEN);
 		__vlan_hwaccel_put_tag(skb, vlan_proto, vlanid);
 	}
+#endif
 }
 
 /**
@@ -5639,12 +5662,9 @@ static void stmmac_dispatch_skb_zc(struct stmmac_priv *priv, u32 queue,
 	}
 
 	stmmac_get_rx_hwtstamp(priv, p, np, skb);
-	if (priv->hw->hw_vlan_en)
-		/* MAC level stripping. */
-		stmmac_rx_hw_vlan(priv, priv->hw, p, skb);
-	else
-		/* Driver level stripping. */
-		stmmac_rx_vlan(priv->dev, skb);
+
+	stmmac_get_rx_vlan(priv, p, skb);
+
 	skb->protocol = eth_type_trans(skb, priv->dev);
 
 	stmmac_get_rx_csum(priv, status, skb);
@@ -6133,12 +6153,7 @@ drain_data:
 
 		stmmac_get_rx_hwtstamp(priv, p, np, skb);
 
-		if (priv->hw->hw_vlan_en)
-			/* MAC level stripping. */
-			stmmac_rx_hw_vlan(priv, priv->hw, p, skb);
-		else
-			/* Driver level stripping. */
-			stmmac_rx_vlan(priv->dev, skb);
+		stmmac_get_rx_vlan(priv, p, skb);
 
 		skb->protocol = eth_type_trans(skb, priv->dev);
 
@@ -6502,11 +6517,10 @@ static int stmmac_set_features(struct net_device *netdev,
 			     features & NETIF_F_RXHASH,
 			     priv->plat->rx_queues_to_use);
 
-	if (netdev->hw_features & NETIF_F_HW_VLAN_CTAG_RX)
-		priv->hw->hw_vlan_en = !!(features & NETIF_F_HW_VLAN_CTAG_RX);
-
 	phylink_rx_clk_stop_block(priv->phylink);
 	stmmac_set_hw_vlan_mode(priv, priv->hw,
+				features & (NETIF_F_HW_VLAN_CTAG_RX |
+					    NETIF_F_HW_VLAN_STAG_RX),
 				features & NETIF_F_HW_VLAN_STAG_TX);
 	phylink_rx_clk_stop_unblock(priv->phylink);
 
@@ -8753,10 +8767,8 @@ static int __stmmac_dvr_probe(struct device *device,
 #ifdef STMMAC_VLAN_TAG_USED
 	/* Both mac100 and gmac support receive VLAN tag detection */
 	ndev->features |= NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX;
-	if (dwmac_is_xmac(priv->plat->core_type)) {
-		ndev->hw_features |= NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX;
-		priv->hw->hw_vlan_en = true;
-	}
+	ndev->hw_features |= NETIF_F_HW_VLAN_CTAG_RX | NETIF_F_HW_VLAN_STAG_RX;
+
 	if (priv->dma_cap.vlhash) {
 		ndev->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
 		ndev->features |= NETIF_F_HW_VLAN_STAG_FILTER;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c
index 77fe0ea31c33..bb0521978453 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_vlan.c
@@ -239,14 +239,15 @@ static void vlan_rx_hw(struct mac_device_info *hw,
 	}
 }
 
-static void vlan_set_hw_mode(struct mac_device_info *hw, bool tx_stag)
+static void vlan_set_hw_mode(struct mac_device_info *hw, bool rx_strip,
+			     bool tx_stag)
 {
 	void __iomem *ioaddr = hw->pcsr;
 	u32 value = readl(ioaddr + VLAN_TAG);
 
 	value &= ~VLAN_TAG_CTRL_EVLS_MASK;
 
-	if (hw->hw_vlan_en)
+	if (rx_strip)
 		/* Always strip VLAN on Receive */
 		value |= VLAN_TAG_STRIP_ALL;
 	else