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

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Message-ID: <87a6exwwxl.fsf@bang-olufsen.dk>
Date:   Fri, 11 Feb 2022 09:54:14 +0000
From:   Alvin Šipraga <ALSI@...g-olufsen.dk>
To:     Luiz Angelo Daros de Luca <luizluca@...il.com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "vivien.didelot@...il.com" <vivien.didelot@...il.com>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "olteanv@...il.com" <olteanv@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "arinc.unal@...nc9.com" <arinc.unal@...nc9.com>,
        Frank Wunderlich <frank-w@...lic-files.de>
Subject: Re: [PATCH net-next] net: dsa: realtek: realtek-mdio: reset before
 setup

Luiz Angelo Daros de Luca <luizluca@...il.com> writes:

> 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.
>
> Reported-by: Frank Wunderlich <frank-w@...lic-files.de>
> Signed-off-by: Luiz Angelo Daros de Luca <luizluca@...il.com>
> ---
>  drivers/net/dsa/realtek/realtek-mdio.c | 19 +++++++++++++++++++
>  drivers/net/dsa/realtek/realtek-smi.c  |  6 ++----
>  drivers/net/dsa/realtek/realtek.h      |  9 ++++++---
>  3 files changed, 27 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/dsa/realtek/realtek-mdio.c b/drivers/net/dsa/realtek/realtek-mdio.c
> index e6e3c1769166..78b419a6cb01 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) {

gpiod_set_value seems tolerant of a NULL gpio_desc pointer, but perhaps
you would like to add the same if statement to realtek-smi so that it
doesn't pretend to reset the chip when the reset GPIO is absent?

> +		dev_info(dev, "asserted RESET\n");
> +		msleep(REALTEK_HW_STOP_DELAY);
> +		gpiod_set_value(priv->reset, 0);
> +		msleep(REALTEK_HW_START_DELAY);
> +		dev_info(dev, "deasserted RESET\n");
> +	}
> +
>  	ret = priv->ops->detect(priv);
>  	if (ret) {
>  		dev_err(dev, "unable to detect switch\n");
> @@ -183,6 +198,10 @@ static void realtek_mdio_remove(struct mdio_device *mdiodev)
>  	if (!priv)
>  		return;
>  
> +	/* leave the device reset asserted */
> +	if (priv->reset)
> +		gpiod_set_value(priv->reset, 1);
> +
>  	dsa_unregister_switch(priv->ds);

Wouldn't you prefer to reset the chip after dsa_unregister_switch()?

Otherwise:

Reviewed-by: Alvin Šipraga <alsi@...g-olufsen.dk>

>  
>  	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 a849b5cbb4e4..cada5386f6a2 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)
>  {
> @@ -426,9 +424,9 @@ 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);
> +	msleep(REALTEK_HW_STOP_DELAY);
>  	gpiod_set_value(priv->reset, 0);
> -	msleep(REALTEK_SMI_HW_START_DELAY);
> +	msleep(REALTEK_HW_START_DELAY);
>  	dev_info(dev, "deasserted RESET\n");
>  
>  	/* Fetch MDIO pins */
> diff --git a/drivers/net/dsa/realtek/realtek.h b/drivers/net/dsa/realtek/realtek.h
> index ed5abf6cb3d6..e7d3e1bcf8b8 100644
> --- a/drivers/net/dsa/realtek/realtek.h
> +++ b/drivers/net/dsa/realtek/realtek.h
> @@ -5,14 +5,17 @@
>   * Copyright (C) 2009-2010 Gabor Juhos <juhosg@...nwrt.org>
>   */
>  
> -#ifndef _REALTEK_SMI_H
> -#define _REALTEK_SMI_H
> +#ifndef _REALTEK_H
> +#define _REALTEK_H
>  
>  #include <linux/phy.h>
>  #include <linux/platform_device.h>
>  #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;
> @@ -142,4 +145,4 @@ void rtl8366_get_ethtool_stats(struct dsa_switch *ds, int port, uint64_t *data);
>  extern const struct realtek_variant rtl8366rb_variant;
>  extern const struct realtek_variant rtl8365mb_variant;
>  
> -#endif /*  _REALTEK_SMI_H */
> +#endif /*  _REALTEK_H */