netdev - Re: [PATCH] net: phy: marvell10g: allow PHY to probe without firmware

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Date:   Mon, 10 Jun 2019 15:13:05 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>, David Miller <davem@...emloft.net>,
        f.fainelli@...il.com, netdev@...r.kernel.org
Subject: Re: [PATCH] net: phy: marvell10g: allow PHY to probe without firmware

On Mon, Jun 10, 2019 at 03:40:10PM +0200, Heiner Kallweit wrote:
> On 06.06.2019 20:36, Andrew Lunn wrote:
> > 65;5402;1c> I don't like too much state changes outside control of the state machine,
> >> like in phy_start / phy_stop / phy_error. I think it would be better
> >> if a state change request is sent to the state machine, and the state
> >> machine decides whether the requested transition is allowed.
> > 
> > Hi Heiner
> > 
> > I initially though that phy_error() would be a good way to do what
> > Russell wants. But the locks get in the way. Maybe add an unlocked
> > version which PHY drivers can use to indicate something fatal has
> > happened?
> > 
> phy_error() switches to PHY_HALTED, therefore phy_start() would start
> another attempt to bring up the PHY. Maybe some new state like
> PHY_PERMANENT_FAILURE could be helpful.  Or do we need a temporary
> failure state?
> 
> After a recent patch from Russell the probe callback returns -ENODEV
> if no firmware is loaded. With the patch starting this discussion
> this would have changed to not failing in probe but preventing the
> PHY from coming up. The commit message missed an explanation what we
> gain with this behavior change.

As previously discussed, it is to allow access to the MDIO bus, and
therefore to allow a userspace tool to program the flash via the
MII ioctls.

At least two people have already independently created such a tool.

-- 
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