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

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Message-ID: <ZK/Xtg3df6n+Nj11@shell.armlinux.org.uk>
Date: Thu, 13 Jul 2023 11:53:42 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Simon Horman <simon.horman@...igine.com>
Cc: Jiawen Wu <jiawenwu@...stnetic.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

On Thu, Jul 13, 2023 at 11:45:59AM +0100, Simon Horman wrote:
> On Thu, Jul 13, 2023 at 11:35:05AM +0100, Russell King (Oracle) wrote:
> > On Thu, Jul 13, 2023 at 11:26:40AM +0100, Simon Horman wrote:
> > > On Wed, Jul 12, 2023 at 02:26:34PM +0800, Jiawen Wu wrote:
> > > > Clear MV_V2_PORT_CTRL_PWRDOWN bit to set power up for 88x3310 PHY,
> > > > it sometimes does not take effect immediately. This will cause
> > > > mv3310_reset() to time out, which will fail the config initialization.
> > > > So add to poll PHY power up.
> > > > 
> > > > Signed-off-by: Jiawen Wu <jiawenwu@...stnetic.com>
> > > 
> > > Hi Jiawen Wu,
> > > 
> > > should this have the following?
> > > 
> > > Fixes: 0a5550b1165c ("bpftool: Use "fallthrough;" keyword instead of comments")
> > 
> > What is that commit? It doesn't appear to be in Linus' tree, it doesn't
> > appear to be in the net tree, nor the net-next tree.
> 
> Hi Russell,
> 
> Sorry, it is bogus. Some sort of cut and paste error on my side
> that pulled in the local commit of an unrelated patch.
> 
> What I should have said is:
> 
> Fixes: 8f48c2ac85ed ("net: marvell10g: soft-reset the PHY when coming out of low power")

Thanks, but I don't think that's appropriate either.

The commit adds a software reset after clearing the power down bit, but
that doesn't have anything to do with mv3310_reset().

There are two places that mv3310_reset() is called, mv3310_config_mdix()
and mv3310_set_edpd(). One of them is in the probe function, after we
have powered up the PHY.

I think we need much more information from the reporter before we can
guess which commit is a problem, if any.

When does the reset time out?
What is the code path that we see mv3310_reset() timing out?
Does the problem happen while resuming or probing?
How soon after clearing the power down bit is mv3310_reset() called?

-- 
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