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

[Clark Wang]

> -----Original Message-----
> From: Russell King <linux@xxxxxxxxxxxxxxx>
> Sent: 2022年11月30日 19:51
> To: Clark Wang <xiaoning.wang@xxxxxxx>
> Cc: peppe.cavallaro@xxxxxx; alexandre.torgue@xxxxxxxxxxx;
> joabreu@xxxxxxxxxxxx; davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx;
> kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; mcoquelin.stm32@xxxxxxxxx;
> andrew@xxxxxxx; hkallweit1@xxxxxxxxx; netdev@xxxxxxxxxxxxxxx;
> linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> 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 11:32:09AM +0000, Clark Wang wrote:
> > Hi Russell,
> >
> > > -----Original Message-----
> > > From: Russell King <linux@xxxxxxxxxxxxxxx>
> > > Sent: 2022年11月30日 19:24
> > > To: Clark Wang <xiaoning.wang@xxxxxxx>
> > > Cc: peppe.cavallaro@xxxxxx; alexandre.torgue@xxxxxxxxxxx;
> > > joabreu@xxxxxxxxxxxx; davem@xxxxxxxxxxxxx;
> edumazet@xxxxxxxxxx;
> > > kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; mcoquelin.stm32@xxxxxxxxx;
> > > andrew@xxxxxxx; hkallweit1@xxxxxxxxx; netdev@xxxxxxxxxxxxxxx;
> > > linux-stm32@xxxxxxxxxxxxxxxxxxxxxxxxxxxx;
> > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> > > 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 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.
> >
> > Thank you very much for your reply!
> >
> > You are right.
> >
> > However, stmmac requires RXC to have a clock input when performing a
> reset(in stmmac_hw_setup()). On our board, RXC is provided by the phy.
> >
> > In WoL mode, this is not a problem, because the phy will not be down
> when suspend. RXC will keep output. But in normal suspend(without WoL),
> the phy will be down, which does not guarantee the output of the RXC of the
> phy. Therefore, the previous code will call phylink_resume() before
> stmmac_hw_setup().
> 
> I think we need phylink_phy_resume() which stmmac can use to resume the
> PHY without resuming phylink, assuming that will output the RXC. Which
> PHY driver(s) are used with stmmac?

Yes, that will be a better way! 
For now, we use AR8031 in drivers/net/phy/at803x.c and
RTL8211F/RTL8211F-VD in drivers/net/phy/realtek.c with stmmac.


Best Regards,
Clark Wang

> 
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