linux-kernel - Re: [PATCH net-next v4 13/12] net: lan865x: optional hardware reset

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Date: Mon, 29 Apr 2024 14:19:34 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Ramón Nordin Rodriguez <ramon.nordin.rodriguez@...roamp.se>
Cc: Parthiban.Veerasooran@...rochip.com, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	horms@...nel.org, saeedm@...dia.com, anthony.l.nguyen@...el.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	corbet@....net, linux-doc@...r.kernel.org, robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
	devicetree@...r.kernel.org, Horatiu.Vultur@...rochip.com,
	ruanjinjie@...wei.com, Steen.Hegelund@...rochip.com,
	vladimir.oltean@....com, UNGLinuxDriver@...rochip.com,
	Thorsten.Kummermehr@...rochip.com, Pier.Beruto@...emi.com,
	Selvamani.Rajagopal@...emi.com, Nicolas.Ferre@...rochip.com,
	benjamin.bigler@...nformulastudent.ch
Subject: Re: [PATCH net-next v4 13/12] net: lan865x: optional hardware reset

> Additionally I figured out why my setup did not work without the HW
> reset, I had missed a pull resistor in the schematic that held the IC in
> reset.

Having a reset controlled by software is a pretty common
design. Something needs to ensure the device is out of reset. It could
be the bootloader, but i don't particularly like that, hiding away
critical things where they are hard to see. So i think having it in
the Linux driver is better.

There is an open question of does the driver need to actually reset
the device, or is it sufficient to ensure it is out of reset? The
wording of the standard suggests a hardware reset cycle is probably
not required, but why did Microchip provide a reset pin?

	Andrew