linux-kernel - RE: [PATCH 1/2] net: phylink: add sync flag mac_ready to fix resume issue with WoL enabled

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Date:   Wed, 30 Nov 2022 11:38:56 +0000
From:   Clark Wang <xiaoning.wang@....com>
To:     Russell King <linux@...linux.org.uk>
CC:     "peppe.cavallaro@...com" <peppe.cavallaro@...com>,
        "alexandre.torgue@...s.st.com" <alexandre.torgue@...s.st.com>,
        "joabreu@...opsys.com" <joabreu@...opsys.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "mcoquelin.stm32@...il.com" <mcoquelin.stm32@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/2] net: phylink: add sync flag mac_ready to fix resume
 issue with WoL enabled


> -----Original Message-----
> From: Russell King <linux@...linux.org.uk>
> Sent: 2022年11月30日 19:33
> To: Clark Wang <xiaoning.wang@....com>
> Cc: peppe.cavallaro@...com; alexandre.torgue@...s.st.com;
> joabreu@...opsys.com; davem@...emloft.net; edumazet@...gle.com;
> kuba@...nel.org; pabeni@...hat.com; mcoquelin.stm32@...il.com;
> andrew@...n.ch; hkallweit1@...il.com; netdev@...r.kernel.org;
> linux-stm32@...md-mailman.stormreply.com;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH 1/2] net: phylink: add sync flag mac_ready to fix resume
> issue with WoL enabled
> 
> On Wed, Nov 30, 2022 at 11:23:42AM +0000, Russell King (Oracle) wrote:
> > On Wed, Nov 30, 2022 at 07:11:47PM +0800, Clark Wang wrote:
> > > Issue we met:
> > > On some platforms, mac cannot work after resumed from the suspend
> > > with WoL enabled.
> > >
> > > The cause of the issue:
> > > 1. phylink_resolve() is in a workqueue which will not be executed
> immediately.
> > >    This is the call sequence:
> > >        phylink_resolve()->phylink_link_up()->pl->mac_ops->mac_link_up()
> > >    For stmmac driver, mac_link_up() will set the correct speed/duplex...
> > >    values which are from link_state.
> > > 2. In stmmac_resume(), it will call stmmac_hw_setup() after called the
> > >    phylink_resume(). stmmac_core_init() is called in function
> > > stmmac_hw_setup(),
> >
> > ... and that is where the problem is. Don't call phylink_resume()
> > before your hardware is ready to see a link-up event.
> 
> ... and while that is being fixed, maybe the stupid code in
> stmmac_resume() can also be fixed:
> 
>         rtnl_lock();
>         if (device_may_wakeup(priv->device) && priv->plat->pmt) {
>                 phylink_resume(priv->phylink);
>         } else {
>                 phylink_resume(priv->phylink);
>                 if (device_may_wakeup(priv->device))
>                         phylink_speed_up(priv->phylink);
>         }
>         rtnl_unlock();
> 
>         rtnl_lock();
> 
> 1. phylink_resume() is always called after that first rtnl_lock(), so there's no
> point it being stupidly in each side of the if().
> 
> 2. the rtnl_unlock() followed by rtnl_lock() is completely unnecessary.
> 
> Thanks.
> 
> --
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