Propagate hardware checksum failures from the descriptor parser to the
caller.

Currently, dwmac4_wrback_get_rx_status() updates stats when the Rx
descriptor signals an IP header or payload checksum error, but it does
not reflect this in its return value. The higher-level stmmac_rx() code
therefore cannot tell that hardware checksum validation failed.

Set the csum_none flag in the returned status when either
RDES1_IP_HDR_ERROR or RDES1_IP_PAYLOAD_ERROR is present. This aligns
dwmac4 with enh_desc_coe_rdes0() and lets stmmac_rx() mark the skb as
CHECKSUM_NONE for software verification.

This is a preparatory step for disabling the hardware filter that drops
frames which do not pass checksum validation.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
index a5fb31eb0192..aac68dc28dc1 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_descs.c
@@ -110,16 +110,20 @@ static int dwmac4_wrback_get_rx_status(struct stmmac_extra_stats *x,
 
 	message_type = (rdes1 & ERDES4_MSG_TYPE_MASK) >> 8;
 
-	if (rdes1 & RDES1_IP_HDR_ERROR)
+	if (rdes1 & RDES1_IP_HDR_ERROR) {
 		x->ip_hdr_err++;
+		ret |= csum_none;
+	}
 	if (rdes1 & RDES1_IP_CSUM_BYPASSED)
 		x->ip_csum_bypassed++;
 	if (rdes1 & RDES1_IPV4_HEADER)
 		x->ipv4_pkt_rcvd++;
 	if (rdes1 & RDES1_IPV6_HEADER)
 		x->ipv6_pkt_rcvd++;
-	if (rdes1 & RDES1_IP_PAYLOAD_ERROR)
+	if (rdes1 & RDES1_IP_PAYLOAD_ERROR) {
 		x->ip_payload_err++;
+		ret |= csum_none;
+	}
 
 	if (message_type == RDES_EXT_NO_PTP)
 		x->no_ptp_rx_msg_type_ext++;
-- 
2.39.5