netdev - RE: [PATCH net] net: phy: marvell10g: fix 88x3310 power up

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Date: Wed, 19 Jul 2023 11:53:31 +0800
From: Jiawen Wu <jiawenwu@...stnetic.com>
To: "'Russell King \(Oracle\)'" <linux@...linux.org.uk>
Cc: "'Simon Horman'" <simon.horman@...igine.com>,
	<kabel@...nel.org>,
	<andrew@...n.ch>,
	<hkallweit1@...il.com>,
	<davem@...emloft.net>,
	<edumazet@...gle.com>,
	<kuba@...nel.org>,
	<pabeni@...hat.com>,
	<netdev@...r.kernel.org>
Subject: RE: [PATCH net] net: phy: marvell10g: fix 88x3310 power up

> > Okay, so how about this for an alternative theory.
> >
> > The PHY is being probed, which places the PHY in power down mode.
> > Then your network driver (which?) gets probed, connects immediately
> > to the PHY, which attempts to power up the PHY - but maybe the PHY
> > hasn't finished powering down yet, and thus delays the powering up.
> >
> > However, according to the functional spec, placing the device in
> > power-down mode as we do is immediate.
> >
> > Please can you try experimenting with a delay in mv3310_config_init()
> > before the call to mv3310_power_up() to see whether that has any
> > beneficial effect?
> 
> I experimented with delays of 100ms to 1s, all reset timed out. Unfortunately,
> the theory doesn't seem to be true. :(

And I tried to add 100ms delay after mv3310_power_up() and before chip->get_mactype(phydev),
it showed that power down bit cleared while reading the reg in mv3310_get_mactype().
Then the reset executed successfully.