On Thu, Jan 22, 2026 at 01:59:21PM +0100, Bastien Curutchet wrote:

Hi Simon,

On 1/20/26 6:17 PM, Simon Horman wrote:

quoted

On Thu, Jan 15, 2026 at 04:57:04PM +0100, Bastien Curutchet (Schneider Electric) wrote:

quoted

KSZ8463 uses the KSZ9893 DSA TAG driver. However, the KSZ8463 doesn't
use the tail tag to convey timestamps to the host as KSZ9893 does. It
uses the reserved fields in the PTP header instead.

Add a KSZ8463-specifig DSA_TAG driver to handle KSZ8463 timestamps.
There is no information in the tail tag to distinguish PTP packets from
others so use the ptp_classify_raw() helper to find the PTP packets and
extract the timestamp from their PTP headers.

Signed-off-by: Bastien Curutchet (Schneider Electric) <redacted>

...

quoted

diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 9170a0148cc43b4213ec4bd8e81d338589671f23..635679402f8a96b29536a91988346a8825bae976 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c

@@ -16,6 +16,7 @@
  #define KSZ9477_NAME "ksz9477"
  #define KSZ9893_NAME "ksz9893"
  #define LAN937X_NAME "lan937x"
+#define KSZ8463_NAME "ksz8463"
  /* Typically only one byte is used for tail tag. */
  #define KSZ_PTP_TAG_LEN			4

@@ -383,6 +384,108 @@ static const struct dsa_device_ops ksz9893_netdev_ops = {
  DSA_TAG_DRIVER(ksz9893_netdev_ops);
  MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9893, KSZ9893_NAME);
+#define KSZ8463_TAIL_TAG_PRIO		GENMASK(4, 3)
+#define KSZ8463_TAIL_TAG_EG_PORT_M	GENMASK(2, 0)
+
+static void ksz8463_xmit_timestamp(struct dsa_port *dp, struct sk_buff *skb)
+{
+	struct ksz_tagger_private *priv;
+	struct ptp_header *ptp_hdr;
+	unsigned int ptp_type;
+	u32 tstamp_raw = 0;
+	s64 correction;
+
+	priv = ksz_tagger_private(dp->ds);
+
+	if (!test_bit(KSZ_HWTS_EN, &priv->state))
+		return;
+
+	if (!KSZ_SKB_CB(skb)->update_correction)
+		return;
+
+	ptp_type = KSZ_SKB_CB(skb)->ptp_type;
+	ptp_hdr = ptp_parse_header(skb, ptp_type);
+	if (!ptp_hdr)
+		return;
+
+	correction = (s64)get_unaligned_be64(&ptp_hdr->correction);
+
+	if (correction < 0) {
+		struct timespec64 ts;
+
+		ts = ns_to_timespec64(-correction >> 16);
+		tstamp_raw = ((ts.tv_sec & 3) << 30) | ts.tv_nsec;
+
+		ptp_hdr->reserved2 = tstamp_raw;

I think that you need to assign a be32 rather than a u32 to reserved2.

Indeed. By testing this back, I realize that this is only needed by the
one-step mode. This series only adds support for two-step so I'll just
remove this part.

Great, thanks.