linux-kernel - [PATCH v3 2/2] net: stmmac: dwmac-imx: enable MAC propagation delay correction for i.MX8MP

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Message-Id: <20230719-stmmac_correct_mac_delay-v3-2-61e63427735e@pengutronix.de>
Date:   Tue, 01 Aug 2023 17:44:30 +0200
From:   Johannes Zink <j.zink@...gutronix.de>
To:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Richard Cochran <richardcochran@...il.com>,
        Russell King <linux@...linux.org.uk>
Cc:     patchwork-jzi@...gutronix.de, netdev@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, Kurt Kanzenbach <kurt@...utronix.de>,
        kernel test robot <lkp@...el.com>,
        Johannes Zink <j.zink@...gutronix.de>
Subject: [PATCH v3 2/2] net: stmmac: dwmac-imx: enable MAC propagation
 delay correction for i.MX8MP

As the i.MX8MP supports reading MAC propagation delay and correcting the
Hardware timestamp counter for additional delays [1], enable the feature
for this SoC.

This reduces phase error of the PPS output from the PTP Hardware Clock
from approx 150ns to 100ns.

[1] i.MX8MP Reference Manual, rev.1 Section 11.7.2.5.3 "Timestamp
correction"

Signed-off-by: Johannes Zink <j.zink@...gutronix.de>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
index 92e06a96757a..645a9454a490 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-imx.c
@@ -42,6 +42,7 @@
 
 struct imx_dwmac_ops {
 	u32 addr_width;
+	u32 flags;
 	bool mac_rgmii_txclk_auto_adj;
 
 	int (*fix_soc_reset)(void *priv, void __iomem *ioaddr);
@@ -311,6 +312,9 @@ static int imx_dwmac_probe(struct platform_device *pdev)
 		goto err_parse_dt;
 	}
 
+	if (data->flags & STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY)
+		plat_dat->flags |= STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY;
+
 	plat_dat->host_dma_width = dwmac->ops->addr_width;
 	plat_dat->init = imx_dwmac_init;
 	plat_dat->exit = imx_dwmac_exit;
@@ -350,6 +354,7 @@ static struct imx_dwmac_ops imx8mp_dwmac_data = {
 	.addr_width = 34,
 	.mac_rgmii_txclk_auto_adj = false,
 	.set_intf_mode = imx8mp_set_intf_mode,
+	.flags = STMMAC_FLAG_HWTSTAMP_CORRECT_LATENCY,
 };
 
 static struct imx_dwmac_ops imx8dxl_dwmac_data = {

-- 
2.39.2