[PATCH net-next 2/3] net: sb1250-mac: Advertise and honor RX checksum offload

[Florian Fainelli <f.fainelli@gmail.com>]

The driver already trusts hardware RX checksum status on supported
chip revisions, but does not advertise NETIF_F_RXCSUM. Consequently,
ethtool does not report the offload or allow it to be disabled.

Advertise RX checksum offload in hw_features and enable it by default
when the existing hardware revision check reports support. Test the
active feature bit in the receive path before marking a packet as
CHECKSUM_UNNECESSARY, so disabling RX checksum offload restores software
verification. Hardware can continue computing checksums while their
results are ignored.

BCM1250 pass 1 does not support the offload and retains the existing
software checksum behavior.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/net/ethernet/broadcom/sb1250-mac.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/sb1250-mac.c b/drivers/net/ethernet/broadcom/sb1250-mac.c
index 1843b52e96f5..546415d3134c 100644
--- a/drivers/net/ethernet/broadcom/sb1250-mac.c
+++ b/drivers/net/ethernet/broadcom/sb1250-mac.c
@@ -1142,8 +1142,8 @@ static int sbdma_rx_process(struct sbmac_softc *sc, struct sbmacdma *d,
 				 * the kernel
 				 */
 				sb->protocol = eth_type_trans(sb,d->sbdma_eth->sbm_dev);
-				/* Check hw IPv4/TCP checksum if supported */
-				if (sc->rx_hw_checksum == ENABLE) {
+				/* Honor the RX checksum offload feature setting. */
+				if (dev->features & NETIF_F_RXCSUM) {
 					if (!((dsc->dscr_a) & M_DMA_ETHRX_BADIP4CS) &&
 					    !((dsc->dscr_a) & M_DMA_ETHRX_BADTCPCS)) {
 						sb->ip_summed = CHECKSUM_UNNECESSARY;
@@ -2214,6 +2214,10 @@ static int sbmac_init(struct platform_device *pldev, long long base)
 
 	/* This is needed for PASS2 for Rx H/W checksum feature */
 	sbmac_set_iphdr_offset(sc);
+	if (sc->rx_hw_checksum == ENABLE) {
+		dev->hw_features |= NETIF_F_RXCSUM;
+		dev->features |= NETIF_F_RXCSUM;
+	}
 
 	sc->mii_bus = mdiobus_alloc();
 	if (sc->mii_bus == NULL) {
-- 
2.53.0