linux-kernel - Re: [PATCH net-next] net: phy: dp8382x: keep WOL setting across suspends

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Date: Fri, 22 Mar 2024 16:34:26 +0000
From: POPESCU Catalin <catalin.popescu@...ca-geosystems.com>
To: Andrew Lunn <andrew@...n.ch>
CC: "hkallweit1@...il.com" <hkallweit1@...il.com>, "linux@...linux.org.uk"
	<linux@...linux.org.uk>, "davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	GEO-CHHER-bsp-development <bsp-development.geo@...ca-geosystems.com>,
	"m.felsch@...gutronix.de" <m.felsch@...gutronix.de>
Subject: Re: [PATCH net-next] net: phy: dp8382x: keep WOL setting across
 suspends

On 22/03/2024 16:56, Andrew Lunn wrote:
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>>> It looks like the issue I'm trying to address in this patch is not
>>> specific to dp8382x. Right now, depending on if the PHY is reset or not
>>> during resume (either through mdio_device reset_gpio/reset_ctrl or
>>> phy_driver soft_reset callback), the WOL configuration is either the PHY
>>> reset value or the BIOS value. I could still make the patch but it
>>> doesn't really make sense to address only dp8382x.
> This is an interesting point. soft_reset the driver is in control
> off. It can preserve the WoL setting over the soft reset.
> A hardware reset is a different matter.
>
> However, if we woke up due to WoL, the PHY never went to sleep, its
> state is intact, so why are we doing a hardware reset?

I checked again the code and the datasheets and I was wrong: the driver 
does a "digital" reset instead of "software hard" reset :
- "digital" reset : registers are preserved
- "software hard" reset : registers are reset
The names are misleading and explains why I made the mistake :)

So, it makes sense to provide a patch for dp8382x that ensure we don't 
forcefully disable WOL on the resume path.

>        Andrew
>