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From: Vladimir Oltean <olteanv@gmail.com>
To: Joakim Zhang <qiangqing.zhang@nxp.com>
Cc: peppe.cavallaro@st.com, alexandre.torgue@foss.st.com,
	joabreu@synopsys.com, davem@davemloft.net, kuba@kernel.org,
	mcoquelin.stm32@gmail.com, linux@armlinux.org.uk,
	netdev@vger.kernel.org, andrew@lunn.ch, f.fainelli@gmail.com,
	hkallweit1@gmail.com, linux-imx@nxp.com
Subject: Re: [PATCH] net: stmmac: fix MAC not working when system resume back with WoL enabled
Date: Wed, 1 Sep 2021 12:21:49 +0300	[thread overview]
Message-ID: <20210901092149.fmap4ac7jxf754ao@skbuf> (raw)
In-Reply-To: <20210901090228.11308-1-qiangqing.zhang@nxp.com>

On Wed, Sep 01, 2021 at 05:02:28PM +0800, Joakim Zhang wrote:
> We can reproduce this issue with below steps:
> 1) enable WoL on the host
> 2) host system suspended
> 3) remote client send out wakeup packets
> We can see that host system resume back, but can't work, such as ping failed.
> 
> After a bit digging, this issue is introduced by the commit 46f69ded988d
> ("net: stmmac: Use resolved link config in mac_link_up()"), which use
> the finalised link parameters in mac_link_up() rather than the
> parameters in mac_config().
> 
> There are two scenarios for MAC suspend/resume:
> 
> 1) MAC suspend with WoL disabled, stmmac_suspend() call
> phylink_mac_change() to notify phylink machine that a change in MAC
> state, then .mac_link_down callback would be invoked. Further, it will
> call phylink_stop() to stop the phylink instance. When MAC resume back,
> firstly phylink_start() is called to start the phylink instance, then
> call phylink_mac_change() which will finally trigger phylink machine to
> invoke .mac_config and .mac_link_up callback. All is fine since
> configuration in these two callbacks will be initialized.
> 
> 2) MAC suspend with WoL enabled, phylink_mac_change() will put link
> down, but there is no phylink_stop() to stop the phylink instance, so it
> will link up again, that means .mac_config and .mac_link_up would be
> invoked before system suspended. After system resume back, it will do
> DMA initialization and SW reset which let MAC lost the hardware setting
> (i.e MAC_Configuration register(offset 0x0) is reset). Since link is up
> before system suspended, so .mac_link_up would not be invoked after
> system resume back, lead to there is no chance to initialize the
> configuration in .mac_link_up callback, as a result, MAC can't work any
> longer.

Have you tried putting phylink_stop in .suspend, and phylink_start in .resume?

> 
> Above description is what I found when debug this issue, this patch is
> just revert broken patch to workaround it, at least make MAC work when
> system resume back with WoL enabled.
> 
> Said this is a workaround, since it has not resolve the issue completely.
> I just move the speed/duplex/pause etc into .mac_config callback, there are
> other configurations in .mac_link_up callback which also need to be
> initialized to work for specific functions.
> 
> Fixes: 46f69ded988d ("net: stmmac: Use resolved link config in mac_link_up()")
> Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
> ---
> 
> Broken patch cannot be reverted directly, so manually modified it.
> 
> I also tried to fix in other ways, but failed to find a better solution,
> any suggestions would be appreciated. Thanks.
> 
> Joakim

Do you know exactly why it used to work prior to this patch?

  parent reply	other threads:[~2021-09-01  9:21 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01  9:02 Joakim Zhang
2021-09-01  9:13 ` Russell King (Oracle)
2021-09-01 10:21   ` Joakim Zhang
2021-09-01 12:56     ` Russell King (Oracle)
2021-09-02  7:01       ` Joakim Zhang
2021-09-01 15:40     ` Heiner Kallweit
2021-09-02  7:35       ` Joakim Zhang
2021-09-01  9:21 ` Vladimir Oltean [this message]
2021-09-01 10:25   ` Joakim Zhang
2021-09-01 10:56     ` Vladimir Oltean
2021-09-01 11:42       ` Joakim Zhang
2021-09-01 13:25         ` Russell King (Oracle)
2021-09-02  7:28           ` Joakim Zhang
2021-09-02  8:32             ` Russell King (Oracle)
2021-09-02 10:26               ` Joakim Zhang
2021-09-02 10:49                 ` Russell King (Oracle)
2021-09-02 11:15                   ` Joakim Zhang
2021-09-02 12:24                     ` Andrew Lunn
2021-09-03  6:51                       ` Joakim Zhang
2021-09-03  8:01                         ` Russell King (Oracle)
2021-09-03  8:39                           ` Joakim Zhang
2021-09-03  9:32                             ` Russell King (Oracle)
2021-09-03 11:04                               ` Joakim Zhang
2021-09-03 12:01                                 ` Russell King (Oracle)
2021-09-03 20:12                                   ` Russell King - ARM Linux admin
2021-09-06  2:29                                     ` Joakim Zhang
2021-09-06  9:34                                       ` Russell King (Oracle)
2021-09-06 10:41                                         ` Joakim Zhang
2021-09-06 11:21                                           ` Russell King (Oracle)
2021-09-06 13:23                                             ` Andrew Lunn
2021-09-07  8:52                                             ` Russell King (Oracle)
2021-09-06  2:21                                   ` Joakim Zhang

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