netdev - [PATCH net-next v2] net: dsa: realtek: realtek-mdio: reset before setup

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Date:   Fri, 11 Feb 2022 23:27:35 -0300
From:   Luiz Angelo Daros de Luca <luizluca@...il.com>
To:     netdev@...r.kernel.org
Cc:     linus.walleij@...aro.org, andrew@...n.ch, vivien.didelot@...il.com,
        f.fainelli@...il.com, olteanv@...il.com, davem@...emloft.net,
        kuba@...nel.org, alsi@...g-olufsen.dk, arinc.unal@...nc9.com,
        Luiz Angelo Daros de Luca <luizluca@...il.com>,
        Frank Wunderlich <frank-w@...lic-files.de>
Subject: [PATCH net-next v2] net: dsa: realtek: realtek-mdio: reset before setup

Some devices, like the switch in Banana Pi BPI R64 only starts to answer
after a HW reset. It is the same reset code from realtek-smi.

In realtek-smi, only assert the reset when the gpio is defined.

Reported-by: Frank Wunderlich <frank-w@...lic-files.de>
Signed-off-by: Luiz Angelo Daros de Luca <luizluca@...il.com>
Tested-by: Frank Wunderlich <frank-w@...lic-files.de>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
Reviewed-by: Alvin Šipraga <alsi@...g-olufsen.dk>
---
 drivers/net/dsa/realtek/realtek-mdio.c | 19 +++++++++++++++++++
 drivers/net/dsa/realtek/realtek-smi.c  | 17 ++++++++++-------
 drivers/net/dsa/realtek/realtek.h      |  3 +++
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/drivers/net/dsa/realtek/realtek-mdio.c b/drivers/net/dsa/realtek/realtek-mdio.c
index 0c5f2bdced9d..fa2339763c71 100644
--- a/drivers/net/dsa/realtek/realtek-mdio.c
+++ b/drivers/net/dsa/realtek/realtek-mdio.c
@@ -152,6 +152,21 @@ static int realtek_mdio_probe(struct mdio_device *mdiodev)
 	/* TODO: if power is software controlled, set up any regulators here */
 	priv->leds_disabled = of_property_read_bool(np, "realtek,disable-leds");
 
+	/* Assert then deassert RESET */
+	priv->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->reset)) {
+		dev_err(dev, "failed to get RESET GPIO\n");
+		return PTR_ERR(priv->reset);
+	}
+
+	if (priv->reset) {
+		dev_dbg(dev, "asserted RESET\n");
+		msleep(REALTEK_HW_STOP_DELAY);
+		gpiod_set_value(priv->reset, 0);
+		msleep(REALTEK_HW_START_DELAY);
+		dev_dbg(dev, "deasserted RESET\n");
+	}
+
 	ret = priv->ops->detect(priv);
 	if (ret) {
 		dev_err(dev, "unable to detect switch\n");
@@ -185,6 +200,10 @@ static void realtek_mdio_remove(struct mdio_device *mdiodev)
 
 	dsa_unregister_switch(priv->ds);
 
+	/* leave the device reset asserted */
+	if (priv->reset)
+		gpiod_set_value(priv->reset, 1);
+
 	dev_set_drvdata(&mdiodev->dev, NULL);
 }
 
diff --git a/drivers/net/dsa/realtek/realtek-smi.c b/drivers/net/dsa/realtek/realtek-smi.c
index 946fbbd70153..a13ef07080a2 100644
--- a/drivers/net/dsa/realtek/realtek-smi.c
+++ b/drivers/net/dsa/realtek/realtek-smi.c
@@ -43,8 +43,6 @@
 #include "realtek.h"
 
 #define REALTEK_SMI_ACK_RETRY_COUNT		5
-#define REALTEK_SMI_HW_STOP_DELAY		25	/* msecs */
-#define REALTEK_SMI_HW_START_DELAY		100	/* msecs */
 
 static inline void realtek_smi_clk_delay(struct realtek_priv *priv)
 {
@@ -426,10 +424,13 @@ static int realtek_smi_probe(struct platform_device *pdev)
 		dev_err(dev, "failed to get RESET GPIO\n");
 		return PTR_ERR(priv->reset);
 	}
-	msleep(REALTEK_SMI_HW_STOP_DELAY);
-	gpiod_set_value(priv->reset, 0);
-	msleep(REALTEK_SMI_HW_START_DELAY);
-	dev_info(dev, "deasserted RESET\n");
+	if (priv->reset) {
+		dev_dbg(dev, "asserted RESET\n");
+		msleep(REALTEK_HW_STOP_DELAY);
+		gpiod_set_value(priv->reset, 0);
+		msleep(REALTEK_HW_START_DELAY);
+		dev_dbg(dev, "deasserted RESET\n");
+	}
 
 	/* Fetch MDIO pins */
 	priv->mdc = devm_gpiod_get_optional(dev, "mdc", GPIOD_OUT_LOW);
@@ -474,7 +475,9 @@ static int realtek_smi_remove(struct platform_device *pdev)
 	dsa_unregister_switch(priv->ds);
 	if (priv->slave_mii_bus)
 		of_node_put(priv->slave_mii_bus->dev.of_node);
-	gpiod_set_value(priv->reset, 1);
+
+	if (priv->reset)
+		gpiod_set_value(priv->reset, 1);
 
 	platform_set_drvdata(pdev, NULL);
 
diff --git a/drivers/net/dsa/realtek/realtek.h b/drivers/net/dsa/realtek/realtek.h
index 3512b832b148..e7d3e1bcf8b8 100644
--- a/drivers/net/dsa/realtek/realtek.h
+++ b/drivers/net/dsa/realtek/realtek.h
@@ -13,6 +13,9 @@
 #include <linux/gpio/consumer.h>
 #include <net/dsa.h>
 
+#define REALTEK_HW_STOP_DELAY		25	/* msecs */
+#define REALTEK_HW_START_DELAY		100	/* msecs */
+
 struct realtek_ops;
 struct dentry;
 struct inode;
-- 
2.35.1