linux-kernel - RE: [PATCH net V2 2/2] net: lan743x: support WOL in MAC even when PHY does not

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Date: Fri, 5 Apr 2024 08:17:22 +0000
From: <Raju.Lakkaraju@...rochip.com>
To: <andrew@...n.ch>
CC: <netdev@...r.kernel.org>, <davem@...emloft.net>, <kuba@...nel.org>,
	<pabeni@...hat.com>, <edumazet@...gle.com>, <linux-kernel@...r.kernel.org>,
	<Bryan.Whitehead@...rochip.com>, <UNGLinuxDriver@...rochip.com>
Subject: RE: [PATCH net V2 2/2] net: lan743x: support WOL in MAC even when PHY
 does not

Hi Andrew,

Sorry for delayed response.

> -----Original Message-----
> From: Andrew Lunn <andrew@...n.ch>
> Sent: Thursday, March 21, 2024 4:23 AM
> To: Raju Lakkaraju - I30499 <Raju.Lakkaraju@...rochip.com>
> Cc: netdev@...r.kernel.org; davem@...emloft.net; kuba@...nel.org;
> pabeni@...hat.com; edumazet@...gle.com; linux-kernel@...r.kernel.org;
> Bryan Whitehead - C21958 <Bryan.Whitehead@...rochip.com>;
> UNGLinuxDriver <UNGLinuxDriver@...rochip.com>
> Subject: Re: [PATCH net V2 2/2] net: lan743x: support WOL in MAC even when
> PHY does not
> 
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
> 
> > +     if (netdev->phydev) {
> > +             ret = phy_ethtool_set_wol(netdev->phydev, wol);
> > +             if (ret != -EOPNOTSUPP && ret != 0)
> > +                     return ret;
> 
> I'm not sure this condition is correct.
> 
> If there is an error, and the error is not EOPNOTSUPP, you want to report that
> error. However, if the PHY can support the WoL configuration, it will return 0,
> and this function should exit, WoL in the MAC is not needed. And doing WoL
> in the PHY consumes less power since you can suspend the MAC.
> 
> So i think it should simply be:
> 
> > +             if (ret != -EOPNOTSUPP)
> > +                     return ret;
> 
> Do you have a board with this MAC with a PHY which does have some WoL
> support. Could you test PHY WoL is used when appropriate?

Yes. 
We have external PHY (Max Linear GPY211C) attach to MAC of PCI11x1x (PCIe Ethernet chip) 
If I don't register the Ethernet module in wakeup source, WOL is not working. Ethernet device power state shows as disable.
i.e.
/sys/devices/pci0000:00/0000:00:1c.4/0000:05:00.0/0000:06:03.0/0000:09:00.0/power/wakeup   <--  disabled

PCI11x1x is PCIe bridge device between PCIe and Ethernet along with other peripherals (i.e. UART, SPI, I2C, USB and PCIe devices)
0000:09:00.0 - Ethernet device
0000:05:00.0 - PCIe Bridge Up link 

When I test the WOL_PHY option on setup (PCI11x1x MAC + GPY211C PHY), observe the following:
1. When enable WOL_PHY by using ethtool (i.e. ethtool -s enp9s0 wol p), GPY211 PHY configure the WOL. After resume from sleep, GPY211 WOL configuration vanish. Observed that gpy_config_init( ) function reset. Is it expected behaviour ? In other mail thread, we discussed that Ethtool configuration should retain after resume from sleep.

2. when WOL configure with ethtool, Either Link-down and Link-up on CLI, WOL configuration vanish. Is it expected behaviour ? Due to this, every time we have to configure WOL through Ethtool.

Based on above information, We need to check for return < 0 condition and return the error. Else enable the wakeup by calling "device_set_wakeup_enable( )" function.

> 
>         Andrew

Thanks,
Raju