netdev - Re: [PATCH net] net: phy: fix WoL handling when suspending the PHY

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Date:   Sat, 22 Sep 2018 19:32:52 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        David Miller <davem@...emloft.net>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net: phy: fix WoL handling when suspending the PHY

On 22.09.2018 18:44, Andrew Lunn wrote:
> On Sat, Sep 22, 2018 at 01:32:55AM +0200, Heiner Kallweit wrote:
>> Actually there's nothing wrong with the two changes, they just
>> revealed a problem which has been existing before.
> 
> Hi Heiner
> 
> This is missing a bit of context. Which two changes? I assume you mean
> the two Fixes:
> 
Right. I should have mentioned that the actual trigger were
reported problems with WoL.

>>
>> Core of the problem is that phy_suspend() suspends the PHY when it
>> should not because of WoL. phy_suspend() checks for WoL already, but
>> this works only if the PHY driver handles WoL (what is rarely the case).
>> Typically WoL is handled by the MAC driver.
>>
>> phylib knows about this and handles it in mdio_bus_phy_may_suspend(),
>> but that's used only when suspending the system, not in other cases
>> like shutdown.
>>
>> This patch basically moves the check for WoL having been activated
>> by the MAC driver into phy_suspend(). mdio_bus_phy_resume() now
>> resumes the PHY only if it's actually suspended. Also don't do
>> anything in phy_suspend() if the PHY is suspended already.
>>
>> Last but not least change phy_detach() to call phy_suspend() before
>> attached_dev is set to NULL. phy_suspend() accesses attached_dev
>> when checking whether the MAC driver activated WoL.
> 
> This sounds like it should be multiple patches, not one. Can it be
> split, or is there two much inter connectivity? Being able to bisect
> could be useful here.
> 
I could split it to two patches:
1. Add phy_may_suspend() and use it in phy_suspend()
2. Remove mdio_bus_phy_may_suspend() and change mdio_bus_phy_suspend()
   and mdio_bus_phy_resume()

Heiner

>       Thanks
> 	Andrew
>