netdev - Re: [PATCH] net: phy: Ensure the state machine is called when phy is UP

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Message-ID: <20160415223026.GD26665@lunn.ch>
Date:	Sat, 16 Apr 2016 00:30:26 +0200
From:	Andrew Lunn <andrew@...n.ch>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:	Florian Fainelli <f.fainelli@...il.com>,
	"David S . Miller" <davem@...emloft.net>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: Ensure the state machine is called when phy is
 UP

On Sat, Apr 16, 2016 at 12:17:11AM +0200, Alexandre Belloni wrote:
> On 16/04/2016 at 00:05:08 +0200, Andrew Lunn wrote :
> > > Trace without my patch:
> > > libphy: MACB_mii_bus: probed
> > > macb f8020000.ethernet eth0: Cadence GEM rev 0x00020120 at 0xf8020000 irq 27 (fc:c2:3d:0c:6e:05)
> > > Micrel KSZ8081 or KSZ8091 f8020000.etherne:01: attached PHY driver [Micrel KSZ8081 or KSZ8091] (mii_bus:phy_addr=f8020000.etherne:01, irq=171)
> > > Micrel KSZ8081 or KSZ8091 f8020000.etherne:01: PHY state change READY -> READY
> > > [...]
> > > Micrel KSZ8081 or KSZ8091 f8020000.etherne:01: PHY state change READY -> READY
> > 
> > Are there some state changes before this? How is it getting to state
> > READY? It would expect it to start in DOWN, from when the phy device
> > was created in phy_device_create().
> > 
> 
> No other changes. I forgot to mention that this is when booting with a
> cable plugged in. Unplugging and replugging the cable makes the link
> detection work fine even without the patch.

Are you tftpbooting? I.e. has the boot loader already done an auto
negotiation?

I've looked at the code and i still don't see how it gets to READY.
What i do see is that when you connect the phy to the MAC, the
interrupt handler is installed. So maybe there are some PHY interrupts
before the interface is opened? Could you put a print in
phy_interrupt().

	Andrew