linux-kernel - Re: [PATCH] net: dsa: lan9303: fix reset on probe

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Date:   Wed, 9 Feb 2022 17:01:24 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Mans Rullgard <mans@...sr.com>
Cc:     Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Vladimir Oltean <olteanv@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Juergen Borleis <kernel@...gutronix.de>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: dsa: lan9303: fix reset on probe

On Wed, Feb 09, 2022 at 02:54:54PM +0000, Mans Rullgard wrote:
> The reset input to the LAN9303 chip is active low, and devicetree
> gpio handles reflect this.  Therefore, the gpio should be requested
> with an initial state of high in order for the reset signal to be
> asserted.  Other uses of the gpio already use the correct polarity.
> 
> Signed-off-by: Mans Rullgard <mans@...sr.com>
> ---
>  drivers/net/dsa/lan9303-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/lan9303-core.c b/drivers/net/dsa/lan9303-core.c
> index aa1142d6a9f5..2de67708bbd2 100644
> --- a/drivers/net/dsa/lan9303-core.c
> +++ b/drivers/net/dsa/lan9303-core.c
> @@ -1301,7 +1301,7 @@ static int lan9303_probe_reset_gpio(struct lan9303 *chip,
>  				     struct device_node *np)
>  {
>  	chip->reset_gpio = devm_gpiod_get_optional(chip->dev, "reset",
> -						   GPIOD_OUT_LOW);
> +						   GPIOD_OUT_HIGH);
>  	if (IS_ERR(chip->reset_gpio))
>  		return PTR_ERR(chip->reset_gpio);

lan9303_handle_reset() does a sleep and then releases the reset. I
don't see anywhere in the driver which asserts the reset first. So is
it actually asserted as part of this getting the GPIO? And if so, does
not this change actually break the reset?

    Andrew