[PATCH net] net: amd-xgbe: support receiving packets with bad FCS

[James <aslan.jnn@gmail.com>]

From: James Nugraha <aslan.jnn@gmail.com>

The driver currently sets the MAC_RCR.DCRCC bit whenever RX is enabled.
This disables hardware FCS validation, causing packets with a bad FCS to
be accepted unconditionally. Users cannot control this behavior because
the driver does not advertise NETIF_F_RXALL.

Advertise NETIF_F_RXALL and disable it by default. Update DCRCC when the
RXALL feature is enabled or disabled, and preserve the selected state
across RX and link stop/start cycles.

Fixes: c5aa9e3b8156 ("amd-xgbe: Initial AMD 10GbE platform driver")
Signed-off-by: James Nugraha <aslan.jnn@gmail.com>
---
Tests:
- Verified invalid-FCS packets are dropped with RXALL disabled.
- Verified invalid-FCS packets are received with RXALL enabled.
- Verified invalid-FCS packets are dropped again after RXALL is disabled.
- Verified the RXALL setting survives RX stop/start.
- Verified the RXALL setting survives link down/up.
- Verified RXALL is disabled by default.

 drivers/net/ethernet/amd/xgbe/xgbe-dev.c  |  3 +--
 drivers/net/ethernet/amd/xgbe/xgbe-drv.c  |  7 ++++++-
 drivers/net/ethernet/amd/xgbe/xgbe-main.c |  7 +++++--
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
index 1f350d3bd..ad2030517 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-dev.c
@@ -3455,7 +3455,8 @@ static void xgbe_enable_rx(struct xgbe_prv_data *pdata)
 	XGMAC_IOWRITE(pdata, MAC_RQC0R, reg_val);
 
 	/* Enable MAC Rx */
-	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, DCRCC, 1);
+	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, DCRCC,
+			   !!(pdata->netdev->features & NETIF_F_RXALL));
 	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, CST, 1);
 	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, ACS, 1);
 	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, RE, 1);
@@ -3466,7 +3467,6 @@ static void xgbe_disable_rx(struct xgbe_prv_data *pdata)
 	unsigned int i;
 
 	/* Disable MAC Rx */
-	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, DCRCC, 0);
 	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, CST, 0);
 	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, ACS, 0);
 	XGMAC_IOWRITE_BITS(pdata, MAC_RCR, RE, 0);
 
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
index 3a79fd054..5fb81bea1 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-drv.c
@@ -2247,13 +2247,14 @@ static int xgbe_set_features(struct net_device *netdev,
 {
 	struct xgbe_prv_data *pdata = netdev_priv(netdev);
 	struct xgbe_hw_if *hw_if = &pdata->hw_if;
-	netdev_features_t rxhash, rxcsum, rxvlan, rxvlan_filter;
+	netdev_features_t rxhash, rxcsum, rxvlan, rxvlan_filter, rxall;
 	int ret = 0;
 
 	rxhash = pdata->netdev_features & NETIF_F_RXHASH;
 	rxcsum = pdata->netdev_features & NETIF_F_RXCSUM;
 	rxvlan = pdata->netdev_features & NETIF_F_HW_VLAN_CTAG_RX;
 	rxvlan_filter = pdata->netdev_features & NETIF_F_HW_VLAN_CTAG_FILTER;
+	rxall = pdata->netdev_features & NETIF_F_RXALL;
 
 	if ((features & NETIF_F_RXHASH) && !rxhash)
 		ret = hw_if->enable_rss(pdata);
@@ -2284,6 +2285,10 @@ static int xgbe_set_features(struct net_device *netdev,
 	else if (!(features & NETIF_F_HW_VLAN_CTAG_FILTER) && rxvlan_filter)
 		hw_if->disable_rx_vlan_filtering(pdata);
 
+	if ((features & NETIF_F_RXALL) != rxall)
+		XGMAC_IOWRITE_BITS(pdata, MAC_RCR, DCRCC,
+				   !!(features & NETIF_F_RXALL));
+
 	pdata->netdev_features = features;
 
 	DBGPR("<--xgbe_set_features\n");
 
diff --git a/drivers/net/ethernet/amd/xgbe/xgbe-main.c b/drivers/net/ethernet/amd/xgbe/xgbe-main.c
index 0e8698928..898146b67 100644
--- a/drivers/net/ethernet/amd/xgbe/xgbe-main.c
+++ b/drivers/net/ethernet/amd/xgbe/xgbe-main.c
@@ -351,7 +351,8 @@ int xgbe_config_netdev(struct xgbe_prv_data *pdata)
 			      NETIF_F_GRO |
 			      NETIF_F_HW_VLAN_CTAG_RX |
 			      NETIF_F_HW_VLAN_CTAG_TX |
-			      NETIF_F_HW_VLAN_CTAG_FILTER;
+			      NETIF_F_HW_VLAN_CTAG_FILTER |
+			      NETIF_F_RXALL;
 
 	if (pdata->hw_feat.rss)
 		netdev->hw_features |= NETIF_F_RXHASH;
@@ -382,2 +382,4 @@ int xgbe_config_netdev(struct xgbe_prv_data *pdata)
 	netdev->features |= netdev->hw_features;
+	/* disable RXALL by default */
+	netdev->features &= ~NETIF_F_RXALL;
 	pdata->netdev_features = netdev->features;