linux-kernel - Re: [PATCH] net: phy: micrel: reconfigure the phy on resume

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Date:   Thu, 14 Jan 2021 12:05:21 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Claudiu.Beznea@...rochip.com, linux@...linux.org.uk
Cc:     andrew@...n.ch, davem@...emloft.net, kuba@...nel.org,
        rjw@...ysocki.net, pavel@....cz, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH] net: phy: micrel: reconfigure the phy on resume

On 14.01.2021 11:41, Claudiu.Beznea@...rochip.com wrote:
> 
> 
> On 14.01.2021 12:25, Russell King - ARM Linux admin wrote:
>>
>> As I've said, if phylib/PHY driver is not restoring the state of the
>> PHY on resume from suspend-to-ram, then that's an issue with phylib
>> and/or the phy driver.
> 
> In the patch I proposed in this thread the restoring is done in PHY driver.
> Do you think I should continue the investigation and check if something
> should be done from the phylib itself?
> 
It was the right move to approach the PM maintainers to clarify whether
the resume PM callback has to assume that power had been cut off and
it has to completely reconfigure the device. If they confirm this
understanding, then:
- the general question remains why there's separate resume and restore
  callbacks, and what restore is supposed to do that resume doesn't
  have to do
- it should be sufficient to use mdio_bus_phy_restore also as resume
  callback (instead of changing each and every PHY driver's resume),
  because we can expect that somebody cutting off power to the PHY
  properly suspends the MDIO bus before

> Thank you,
> Claudiu Beznea
> 
>>
>> --
>> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
>> FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!