netdev - RE: [PATCH net-next V1 3/4] net: stmmac: Reconfigure the PHY WOL settings in stmmac

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Date:   Wed, 23 Jun 2021 10:06:44 +0000
From:   "Voon, Weifeng" <weifeng.voon@...el.com>
To:     Andrew Lunn <andrew@...n.ch>,
        "Ling, Pei Lee" <pei.lee.ling@...el.com>
CC:     Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Jose Abreu <joabreu@...opsys.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "Maxime Coquelin" <mcoquelin.stm32@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "Ong, Boon Leong" <boon.leong.ong@...el.com>,
        Wong Vee Khee <vee.khee.wong@...ux.intel.com>,
        "Wong, Vee Khee" <vee.khee.wong@...el.com>,
        "Tan, Tee Min" <tee.min.tan@...el.com>,
        "Sit, Michael Wei Hong" <michael.wei.hong.sit@...el.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 net-next V1 3/4] net: stmmac: Reconfigure the PHY WOL
 settings in stmmac_resume()

> > From: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@...el.com>
> >
> > After PHY received a magic packet, the PHY WOL event will be triggered
> > then PHY WOL event interrupt will be disarmed.
> > Ethtool settings will remain with WOL enabled after a S3/S4 suspend
> > resume cycle as expected. Hence,the driver should reconfigure the PHY
> > settings to reenable/disable WOL depending on the ethtool WOL settings
> > in the resume flow.
> 
> Please could you explain this a bit more? I'm wondering if you have a
> PHY driver bug. PHY WOL should remain enabled until it is explicitly
> disabled.
> 
> 	Andrew

Let's take Marvell 1510 as example. 

As explained in driver/net/phy/marvell.c
1773 >------->-------/* If WOL event happened once, the LED[2] interrupt pin
1774 >------->------- * will not be cleared unless we reading the interrupt status
1775 >------->------- * register. 

The WOL event will not able trigger again if the driver does not clear
the interrupt status.
Are we expecting PHY driver will automatically clears the interrupt
status rather than trigger from the MAC driver?

After scanning through all the PHY drivers, the drivers only touches 
the WOL settings in the get|set_wol() callbacks. Hence, I think that 
currently there are no PHY drivers that clear the WOL status.
Unless the PHY able to self-clear the WOL event status, the PHY WOL
would not able to remain enabled after resume from S3/S4.
Therefore, we implemented it in the MAC driver to reconfigure the PHY
WOL during the MAC resume() flow.      

Weifeng