netdev - Re: [PATCH] net: phy: at803x: Improve hibernation support on start up

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Message-ID: <20230810043242.GB13300@pengutronix.de>
Date: Thu, 10 Aug 2023 06:32:42 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Marek Vasut <marex@...x.de>
Cc: Andrew Lunn <andrew@...n.ch>, Wei Fang <wei.fang@....com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Oleksij Rempel <linux@...pel-privat.de>,
	Paolo Abeni <pabeni@...hat.com>,
	Russell King <linux@...linux.org.uk>
Subject: Re: [PATCH] net: phy: at803x: Improve hibernation support on start up

On Thu, Aug 10, 2023 at 02:49:55AM +0200, Marek Vasut wrote:
> On 8/10/23 00:06, Andrew Lunn wrote:
> > On Wed, Aug 09, 2023 at 11:34:19PM +0200, Marek Vasut wrote:
> > > On 8/9/23 15:40, Andrew Lunn wrote:
> > > > > > Hm.. how about officially defining this PHY as the clock provider and disable
> > > > > > PHY automatic hibernation as long as clock is acquired?
> > > > > > 
> > > > > Sorry, I don't know much about the clock provider/consumer, but I think there
> > > > > will be more changes if we use clock provider/consume mechanism.
> > > > 
> > > > Less changes is not always best. What happens when a different PHY is
> > > > used?
> > > 
> > > Then the system wouldn't be affected by this AR803x specific behavior.
> > 
> > Do you know it really is specific to the AR803x? Turning the clock off
> > seams a reasonable thing to do when saving power, or when there is no
> > link partner.
> 
> This hibernation behavior seem specific to this PHY, I haven't seen it on
> another PHY connected to the EQoS so far.

Hm.. if I see it correctly I have right now kind of similar issues with
Microchip KSZ9893 switch attached to EQoS. The switch is clock
provider and I need to make sure that switch has CPU port enabled before
probing the ethernet controller.

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