netdev - Re: [PATCH net-next 0/2] net: phy: add generic ndo_do_ioctl handler phy_do

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Date:   Sun, 19 Jan 2020 23:28:14 +0100
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-next 0/2] net: phy: add generic ndo_do_ioctl handler
 phy_do_ioctl

On 19.01.2020 21:50, Andrew Lunn wrote:
>> Speaking for r8169:
>> If interface is up and cable detached, then it runtime-suspends
>> and goes into PCI D3 (chip and MDIO bus not accessible).
>> But ndev is "running" and PHY is attached.
> 
> Hi Heiner
> 
Hi Andrew,

> And how does it get out of this state? I assume the PHY interrupts
> when the link is established. Is phylib handling this interrupt? If
> so, when phylib accesses the MDIO bus, the bus needs to be runtime PM
> aware. And if the bus is runtime PM aware, the IOCTL handler should
> work, when the device is runtime suspended.  If the MAC is handling
> this interrupt, and it is the MAC interrupt handler which is run-time
> unsuspending, then the ioctl handler is not going to work unless it
> also runtime unsuspends.
> 
The chip (wherever the magic happens) generates a PCI PME if WoL
config includes detection of physical link-up. The PCI core then
runtime-resumes the device.
I'd prefer the ioctl to return an error here instead of e.g.
0xffff for a register read.

> 	Andrew
> 
Heiner