[PATCH net 3/4] net: ti: icssg: Use undirected TX tag for XDP zero copy in HSR offload mode

[Meghana Malladi <m-malladi@ti.com>]

emac_xsk_xmit_zc() has the same issue as the fixed emac_xmit_xdp_frame():
it always sets the CPPI5 descriptor destination tag to emac->port_id,
which directs the PRU firmware to transmit on only one slave port in HSR
mode, breaking redundancy.

Apply the same fix: in HSR offload mode when NETIF_F_HW_HSR_DUP is set,
use PRUETH_UNDIRECTED_PKT_DST_TAG (port 0) so the PRU duplicates frames
to both ports. Also set PRUETH_UNDIRECTED_PKT_TAG_INS when
NETIF_F_HW_HSR_TAG_INS is set so the PRU re-inserts the HSR sequence tag
that was stripped by the PRU on RX before the XDP program saw the frame.

This ensures XSK XDP_TX frames in HSR mode are treated identically to
skb TX via hsr0.

Fixes: 8756ef2eb078 ("net: ti: icssg-prueth: Add AF_XDP zero copy for TX")
Signed-off-by: Meghana Malladi <m-malladi@ti.com>
---
 drivers/net/ethernet/ti/icssg/icssg_common.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ti/icssg/icssg_common.c b/drivers/net/ethernet/ti/icssg/icssg_common.c
index ede32f266729..82ddef9c17d5 100644
--- a/drivers/net/ethernet/ti/icssg/icssg_common.c
+++ b/drivers/net/ethernet/ti/icssg/icssg_common.c
@@ -105,6 +105,7 @@ static int emac_xsk_xmit_zc(struct prueth_emac *emac,
 	struct xdp_desc xdp_desc;
 	int num_tx = 0, pkt_len;
 	int descs_avail, ret;
+	u32 dst_tag_id;
 	u32 *epib;
 	int i;
 
@@ -137,9 +138,17 @@ static int emac_xsk_xmit_zc(struct prueth_emac *emac,
 		epib[0] = 0;
 		epib[1] = 0;
 		cppi5_hdesc_set_pktlen(host_desc, pkt_len);
-		cppi5_desc_set_tags_ids(&host_desc->hdr, 0,
-					(emac->port_id | (q_idx << 8)));
+		dst_tag_id = emac->port_id | (q_idx << 8);
+
+		if (emac->prueth->is_hsr_offload_mode &&
+		    (ndev->features & NETIF_F_HW_HSR_DUP))
+			dst_tag_id = PRUETH_UNDIRECTED_PKT_DST_TAG;
+
+		if (emac->prueth->is_hsr_offload_mode &&
+		    (ndev->features & NETIF_F_HW_HSR_TAG_INS))
+			epib[1] |= PRUETH_UNDIRECTED_PKT_TAG_INS;
 
+		cppi5_desc_set_tags_ids(&host_desc->hdr, 0, dst_tag_id);
 		k3_udma_glue_tx_dma_to_cppi5_addr(tx_chn->tx_chn, &dma_buf);
 		cppi5_hdesc_attach_buf(host_desc, dma_buf, pkt_len, dma_buf,
 				       pkt_len);
-- 
2.43.0