linux-kernel - [PATCH net-next v1 4/4] net: stmmac: use delays reported by the PHY driver to correct MAC propagation delay

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Date: Wed, 17 Apr 2024 18:43:16 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Jose Abreu <joabreu@...opsys.com>,
	"David S. Miller" <davem@...emloft.net>,
	Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	Woojung Huh <woojung.huh@...rochip.com>,
	Arun Ramadoss <arun.ramadoss@...rochip.com>,
	Richard Cochran <richardcochran@...il.com>,
	Russell King <linux@...linux.org.uk>
Cc: Oleksij Rempel <o.rempel@...gutronix.de>,
	kernel@...gutronix.de,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	UNGLinuxDriver@...rochip.com,
	linux-stm32@...md-mailman.stormreply.com
Subject: [PATCH net-next v1 4/4] net: stmmac: use delays reported by the PHY driver to correct MAC propagation delay

Now after PHY drivers are able to report data path delays, we can use
them in the MAC drivers for the delay correction.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h    |  2 ++
 .../ethernet/stmicro/stmmac/stmmac_hwtstamp.c   |  4 ++++
 .../net/ethernet/stmicro/stmmac/stmmac_main.c   | 17 ++++++++++++++++-
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index dddcaa9220cc3..6db54ce33ea72 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -288,6 +288,8 @@ struct stmmac_priv {
 	u32 sub_second_inc;
 	u32 systime_flags;
 	u32 adv_ts;
+	u64 phy_tx_delay_ns;
+	u64 phy_rx_delay_ns;
 	int use_riwt;
 	int irq_wake;
 	rwlock_t ptp_lock;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
index f05bd757dfe52..bbf284cb7cc2a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
@@ -71,6 +71,8 @@ static void hwtstamp_correct_latency(struct stmmac_priv *priv)
 	/* MAC-internal ingress latency */
 	scaled_ns = readl(ioaddr + PTP_TS_INGR_LAT);
 
+	scaled_ns += priv->phy_rx_delay_ns << 16;
+
 	/* See section 11.7.2.5.3.1 "Ingress Correction" on page 4001 of
 	 * i.MX8MP Applications Processor Reference Manual Rev. 1, 06/2021
 	 */
@@ -95,6 +97,8 @@ static void hwtstamp_correct_latency(struct stmmac_priv *priv)
 	/* MAC-internal egress latency */
 	scaled_ns = readl(ioaddr + PTP_TS_EGR_LAT);
 
+	scaled_ns += priv->phy_tx_delay_ns << 16;
+
 	reg_tsec = scaled_ns >> 16;
 	reg_tsecsns = scaled_ns & 0xff00;
 
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index fe3498e86de9d..30c7c278b7062 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1097,8 +1097,23 @@ static void stmmac_mac_link_up(struct phylink_config *config,
 	if (priv->dma_cap.fpesel)
 		stmmac_fpe_link_state_handle(priv, true);
 
-	if (priv->plat->flags & STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY)
+	if (priv->plat->flags & STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY) {
+		int ret = 0;
+
+		if (phy)
+			ret = phy_get_timesync_data_path_delays(phy,
+								&priv->phy_tx_delay_ns,
+								&priv->phy_rx_delay_ns);
+		if (!phy || ret) {
+			if (ret != -EOPNOTSUPP)
+				netdev_err(priv->dev, "Failed to get PHY delay: %pe\n",
+					   ERR_PTR(ret));
+			priv->phy_tx_delay_ns = 0;
+			priv->phy_rx_delay_ns = 0;
+		}
+
 		stmmac_hwtstamp_correct_latency(priv, priv);
+	}
 }
 
 static const struct phylink_mac_ops stmmac_phylink_mac_ops = {
-- 
2.39.2