cpsw fails to come up once in a while

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

Hi,

So I have this test where my am335x-evm boots over NFS and once it 
completes it does it again. It works most of the time :) However once it
like 100 attempts it does not. After the reset u-boot complains about
ethernet timeout and linux has also no luck:

| U-Boot 2013.04-00274-ga71d45d (May 27 2013 - 12:41:57)
| 
|…
| Net:   Phy not found
| PHY reset timed out
| cpsw, usb_ether
| Hit any key to stop autoboot:  1 ^H^H^H 0 
| link up on port 0, speed 1000, full duplex
| Using cpsw device
| TFTP from server 172.123.10.10; our IP address is 172.123.10.3
| Filename 'am335x/zImage'.
| Load address: 0x80200000
| Loading: *^H#################################################################
|          #################################################################
|          #######################################
|          509.8 KiB/s

So the PHY was not found but somehow it managed to fetch the kernel over
network and boot it. The linux driver did not want to continue:

| omap_i2c 4802a000.i2c: bus 1 rev0.11 at 100 kHz
| davinci_mdio 4a101000.mdio: davinci mdio revision 1.6
| davinci_mdio 4a101000.mdio: no live phy, scanning all
| davinci_mdio: probe of 4a101000.mdio failed with error -5
| Random MACID = 16:74:44:51:f1:0f
| gpio-keys volume_keys.6: Unable to claim irq 0; error -22
| gpio-keys: probe of volume_keys.6 failed with error -22
| omap_rtc 44e3e000.rtc: setting system clock to 2000-01-01 03:22:52 UTC (946696972)
| net eth0: initializing cpsw version 1.12 (0)
| libphy: PHY 4a101000.mdio:00 not found
| net eth0: phy 4a101000.mdio:00 not found on slave 0
| libphy: PHY 4a101000.mdio:01 not found
| net eth0: phy 4a101000.mdio:01 not found on slave 1
| Waiting up to 110 more seconds for network.

so the driver also failed to find a PHY and gave up.
Is this something known?

Sebastian