All of lore.kernel.org
 help / color / mirror / Atom feed
From: Joakim Zhang <qiangqing.zhang@nxp.com>
To: Russell King <linux@armlinux.org.uk>, "andrew@lunn.ch" <andrew@lunn.ch>
Cc: Vladimir Oltean <olteanv@gmail.com>,
	"peppe.cavallaro@st.com" <peppe.cavallaro@st.com>,
	"alexandre.torgue@foss.st.com" <alexandre.torgue@foss.st.com>,
	"joabreu@synopsys.com" <joabreu@synopsys.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"mcoquelin.stm32@gmail.com" <mcoquelin.stm32@gmail.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"f.fainelli@gmail.com" <f.fainelli@gmail.com>,
	"hkallweit1@gmail.com" <hkallweit1@gmail.com>,
	dl-linux-imx <linux-imx@nxp.com>
Subject: RE: [PATCH] net: stmmac: fix MAC not working when system resume back with WoL enabled
Date: Thu, 2 Sep 2021 11:15:43 +0000	[thread overview]
Message-ID: <DB8PR04MB6795C37D718096E7CA1AA72DE6CE9@DB8PR04MB6795.eurprd04.prod.outlook.com> (raw)
In-Reply-To: <20210902104943.GD22278@shell.armlinux.org.uk>


Hi Russell,

> -----Original Message-----
> From: Russell King <linux@armlinux.org.uk>
> Sent: 2021年9月2日 18:50
> To: Joakim Zhang <qiangqing.zhang@nxp.com>
> Cc: Vladimir Oltean <olteanv@gmail.com>; peppe.cavallaro@st.com;
> alexandre.torgue@foss.st.com; joabreu@synopsys.com;
> davem@davemloft.net; kuba@kernel.org; mcoquelin.stm32@gmail.com;
> netdev@vger.kernel.org; andrew@lunn.ch; f.fainelli@gmail.com;
> hkallweit1@gmail.com; dl-linux-imx <linux-imx@nxp.com>
> Subject: Re: [PATCH] net: stmmac: fix MAC not working when system resume
> back with WoL enabled
> 
> On Thu, Sep 02, 2021 at 10:26:13AM +0000, Joakim Zhang wrote:
> >
> > Hi Russell,
> >
> > Thanks a lot!
> >
> > > -----Original Message-----
> > > From: Russell King <linux@armlinux.org.uk>
> > > Sent: 2021年9月2日 16:32
> > > To: Joakim Zhang <qiangqing.zhang@nxp.com>
> > > Cc: Vladimir Oltean <olteanv@gmail.com>; peppe.cavallaro@st.com;
> > > alexandre.torgue@foss.st.com; joabreu@synopsys.com;
> > > davem@davemloft.net; kuba@kernel.org; mcoquelin.stm32@gmail.com;
> > > netdev@vger.kernel.org; andrew@lunn.ch; f.fainelli@gmail.com;
> > > hkallweit1@gmail.com; dl-linux-imx <linux-imx@nxp.com>
> > > Subject: Re: [PATCH] net: stmmac: fix MAC not working when system
> > > resume back with WoL enabled
> > >
> > > On Thu, Sep 02, 2021 at 07:28:44AM +0000, Joakim Zhang wrote:
> > > >
> > > > Hi Russell,
> > > >
> > > > > -----Original Message-----
> > > > > From: Russell King <linux@armlinux.org.uk>
> > > > > Sent: 2021年9月1日 21:26
> > > > > To: Joakim Zhang <qiangqing.zhang@nxp.com>
> > > > > Cc: Vladimir Oltean <olteanv@gmail.com>; peppe.cavallaro@st.com;
> > > > > alexandre.torgue@foss.st.com; joabreu@synopsys.com;
> > > > > davem@davemloft.net; kuba@kernel.org;
> mcoquelin.stm32@gmail.com;
> > > > > netdev@vger.kernel.org; andrew@lunn.ch; f.fainelli@gmail.com;
> > > > > hkallweit1@gmail.com; dl-linux-imx <linux-imx@nxp.com>
> > > > > Subject: Re: [PATCH] net: stmmac: fix MAC not working when
> > > > > system resume back with WoL enabled
> > > > >
> > > > > This means you need to have the phy <-> mac link up during
> > > > > suspend, and in that case, yes, you do not want to call
> > > > > phylink_stop() or phylink_start().
> > > >
> > > > I have a question here, why need to have the phy<->mac link up
> > > > during
> > > suspend?
> > >
> > > You need the link up because I think from reading the code, it is
> > > _not_ the PHY that is triggering the wakeup in the configuration you are
> using, but the MAC.
> > >
> > > If the link is down, the PHY can't pass the received packet to the
> > > MAC, and the MAC can't recognise the magic packet.
> >
> > Per my understanding, if use PHY-based wakeup, PHY should be active,
> > and MAC can be totally suspended. When PHY receive the magic packets,
> > it will generate a signal via wakeup PIN (PHY seems all have such PIN) to
> inform SoC, we can use this to wake up the system.
> > Please correct me if I misunderstand.
> 
> Correct.
> 
> > > FEC doesn't have this. FEC relies purely on the PHY detecting the
> > > magic packet, which is much more power efficient, because it means
> > > the MAC doesn't need to be powered up and operational while the rest of
> the system is suspended.
> >
> > AFAIK, FEC also use the MAC-based wakeup, when enable FEC WoL feature,
> > it will keep MAC receive logic active, PHY pass the received packets
> > to MAC, if MAC detects the magic packets, it will generate an interrupt to
> wake up the system.
> 
> You're right.
> 
> However, as the PHY is not configured for WoL with FEC, and
> fec_suspend() unconditionally calls phy_stop() which will place the PHY into
> suspend mode. 

No, phylib has much logic to avoid putting PHY into suspended state if either MAC or
PHY WoL active. Such as in phy_suspend(),
	if (wol.wolopts || (netdev && netdev->wol_enabled))
		return -EBUSY;

Or in mdio_bus_phy_may_suspend()...

> Maybe the PHY driver there has a NULL phydrv->suspend
> method? However, I see that at803x has suspend methods (which I believe is
> the PHY that gets used with i.MX products) which will power down the PHY.

Yes, we have many boards use AR8031 PHY, and all support MAC-based wakeup feature.

> So, how does this work with FEC - because right now I can't see it working, but
> you say it does.
>
> I think we need to understand how FEC is working here, and we need a deeper
> understanding why stmmac isn't working.

Emm, @andrew@lunn.ch, Andrew is much familiar with FEC, and PHY maintainers,
Could you please help put insights here if possible?

> I don't have any iMX systems that support WoL, so this isn't something I can
> test. (SolidRun's i.MX platforms do not support any kind of system power down,
> so suspend isn't supported.)

Understood, thanks.

Best Regards,
Joakim Zhang

  reply	other threads:[~2021-09-02 11:15 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
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 [this message]
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=DB8PR04MB6795C37D718096E7CA1AA72DE6CE9@DB8PR04MB6795.eurprd04.prod.outlook.com \
    --to=qiangqing.zhang@nxp.com \
    --cc=alexandre.torgue@foss.st.com \
    --cc=andrew@lunn.ch \
    --cc=davem@davemloft.net \
    --cc=f.fainelli@gmail.com \
    --cc=hkallweit1@gmail.com \
    --cc=joabreu@synopsys.com \
    --cc=kuba@kernel.org \
    --cc=linux-imx@nxp.com \
    --cc=linux@armlinux.org.uk \
    --cc=mcoquelin.stm32@gmail.com \
    --cc=netdev@vger.kernel.org \
    --cc=olteanv@gmail.com \
    --cc=peppe.cavallaro@st.com \
    --subject='RE: [PATCH] net: stmmac: fix MAC not working when system resume back with WoL enabled' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.