linux-kernel - Re: [PATCH net-next v2 3/3] net: dsa: microchip: Set SPI as bus interface during reset for KSZ8463

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Message-ID: <d7554ede-1405-4e93-8305-2085fbf38701@lunn.ch>
Date: Tue, 16 Sep 2025 00:00:15 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Bastien Curutchet <bastien.curutchet@...tlin.com>
Cc: Woojung Huh <woojung.huh@...rochip.com>, UNGLinuxDriver@...rochip.com,
	Vladimir Oltean <olteanv@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Marek Vasut <marex@...x.de>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Miquèl Raynal <miquel.raynal@...tlin.com>,
	Pascal Eberhard <pascal.eberhard@...com>, netdev@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v2 3/3] net: dsa: microchip: Set SPI as bus
 interface during reset for KSZ8463

On Fri, Sep 12, 2025 at 11:09:14AM +0200, Bastien Curutchet wrote:
> At reset, the KSZ8463 uses a strap-based configuration to set SPI as
> bus interface. SPI is the only bus supported by the driver. If the
> required pull-ups/pull-downs are missing (by mistake or by design to
> save power) the pins may float and the configuration can go wrong
> preventing any communication with the switch.
> 
> Introduce a ksz8463_configure_straps_spi() function called during the
> device reset. It relies on the 'strap-rxd*-gpios' OF properties and the
> 'reset' pinmux configuration to enforce SPI as bus interface.
> 
> Signed-off-by: Bastien Curutchet (Schneider Electric) <bastien.curutchet@...tlin.com>

Thanks for updating the commit messages, it is now a lot clearer why
this is needed.

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew