so, I have a couple of days to play with our (my crew of crazy friends)
Sonoko project, which has different boards running Linux, and the road-map is still ... sit, relax, and ... yes, it's all still a bloody mess
![Flogging A Dead Horse :horse:](https://www.eevblog.com/forum/Smileys/default/DeadHorse.gif.pagespeed.ce.kBWvHKqCd1.gif)
Anyway, one of the weird problems we have found is related to the Ethernet auto-negotiation, which is still a mystery.
Each node does bootstrap from the network via tftp, so it's very important that each node uses the maximal speed possible because the kernel image is of 8Mbyte and the ramrootfs is of 64Mbyte.
A lot of Mbyte to be uploaded
![Shocked :o](https://www.eevblog.com/forum/Smileys/default/xshocked.gif.pagespeed.ic.CrwtrNUjLO.png)
Each graphic node has a PowerPC405GP embedded CPU with an MII channel to the Ethernet PHY, which should be responsible for both speed { 10Mbps, 100Mbps} and {half, full} duplex auto-negotiation, while the router-node has three fast-ethernet ports configured to autonegotiate the maximal speed possible, but ... when you look at the configuration reported by U-boot on each of the graphic nodes, it randomly looks like "a deranged dog on speed" (
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/xgrin.gif.pagespeed.ic.QVVz6XIT20.png)
).
Here it is an example
# tftpboot 800000 kernel
ENET Speed is 100 Mbps - FULL duplex connection (EMAC0)
Using ppc_4xx_eth0 device
u-boot says 100Mbps full duplex!
Does it lie? Well, the Linux router says this
# ethtool eth1
Settings for eth1:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: Yes
Speed: 10Mb/s
Duplex: Half
Port: MII
PHYAD: 1
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0x00000000 (0)
Link detected: no
10Mbps half duplex
100Mbps full duplex != 10Mbps half duplex .... do have to trust the router because a second laptop has just confirmed that the graphic node is *somehow* failing the auto-negotiate, so it has forced the link to be 10Mbps half-duplex.
In fact, the Ethernet PHY is a
DP83843 chip which exposes some pins for Auto-Negotiation and other pins are used to indicate Duplex, Link, Receive and Transmit, Link, Collision, and Speed status. By reading their logic status ... yet again confirmed what the router says: 10Mbps half-duplex
![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/xfacepalm.gif.pagespeed.ic.EBDwh1hCfo.png)
So u-boot does lie!
One of the question is: why? why does it fail? It's not clear how and why the auto-negotiate protocol does work at this point.
-
Perhaps, I cannot even exclude a bug in u-boot, but in my mind, this is less convincing.
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Anyway, I do not even know how to proceed, and where I have to investigate.