[U-Boot] Fw: TFTP fails when using network switch

[L. A. Linden Levy]

Can someone tell me how to use the mii command? I have the following
from a dump:

uBOOT=>> mii dump
MII not complete
0.     (ffff)                 -- PHY control register --
 (8000:8000) 0.15    =     1    reset
 (4000:4000) 0.14    =     1    loopback
 (2040:2040) 0. 6,13 =   b11    speed selection = ??? Mbps
 (1000:1000) 0.12    =     1    A/N enable
 (0800:0800) 0.11    =     1    power-down
 (0400:0400) 0.10    =     1    isolate
 (0200:0200) 0. 9    =     1    restart A/N
 (0100:0100) 0. 8    =     1    duplex = full
 (0080:0080) 0. 7    =     1    collision test enable
 (003f:003f) 0. 5- 0 =    63    (reserved)

On Wed, Jan 7, 2009 at 12:58 PM, Jerry Van Baren <gerald.vanbaren at ge.com> wrote:
> Ulf Samuelsson wrote:
>>
>> ons 2009-01-07 klockan 07:52 -0500 skrev Jerry Van Baren:
>>>
>>> Wolfgang Denk wrote:
>>>>
>>>> Dear Ulf Samuelsson,
>>>>
>>>> In message <1231282371.32308.276.camel at elrond.atmel.com> you wrote:
>>>>>
>>>>> It was tracked down to the autoconfiguration of the Ethernet PHY, so
>>>>> one of the PHYs ended up in 100 Mbps Half Duplex (think that was the switch)
>>>>> while the other PHY ended up in 100 MBps Full Duplex.
>>>>
>>>> That would most probably be a bug in the U-Boot ethernet driver, then.
>>>>
>>>> Best regards,
>>>>
>>>> Wolfgang Denk
>>>
>>> If auto-negotiation fails, the default is half duplex (10 or 100 - the
>>> speed can be discovered independent of the autonegotiation by the encoding).
>>>
>>> Ulf's recollection that the switch was half duplex would indicate that
>>> the cheap switch did not autonegotiate properly, but u-boot did.  This could
>>> be a u-boot bug (not setting up the negotiation properly), but more likely
>>> would be a switch problem (not handling the u-boot auto-neg options
>>> properly).
>>>
>>
>> Don't remember all details, since it was 4 years ago.
>> I talked to D-Link support and they claimed that the standard
>> was to fall back to one of the options, if autonegotiation failed.
>
> Autonegotiation enabled but fails => half duplex.  It's in the spec.
>
>> The customer might have had a PHY without autonegotation which
>> was hardwired to 100 Mbps full duplex.
>
> Manually configured (autoneg disabled) is no problem, *AS LONG AS* both
> sides are manually configured to the same configuration.  The problem is
> when one side is configured to autonegotiate and the other side is set to
> full duplex.  The autonegotiation side is unable to negotiate with the
> manually configured side, so it falls back to half duplex at whatever rate
> is being used (10/100, determined from the encoding on the wire).
>
> It sorta works until there is more than a few packets on the wire, at which
> time the half duplex end sees the full duplex packets as collisions and the
> error rate (and runt packets) skyrockets because the half duplex side keeps
> aborting packets.
>
> It sounds like, in your case, the computer end was manually configured to be
> (100bT) full duplex but the (cheap unmanaged) switch was still running
> auto-negotiation.  Recipe for disaster.
>
>> With little communication, the packages were sent where this caused some
>> problems.
>
> Oh yeah, in spades, but only when the wire gets busier.
>
> gvb
>
>



-- 
 --
---------------------------------------------
Loren A. Linden Levy
Department of Physics
390 UCB
University of Colorado
Boulder, CO   80309-0390
Tel:   303-735-6146 (CU) / +049 040 8998 4789 (DESY)
Fax:   303-492-3352 (CU) / +049 040 8998 4034 (DESY)
Cell:  303-332-2768 (U.S.) / +049 (0)151 5496 1831 (Germany)
Email: Loren.Lindenlevy at colorado.edu
url:   http://up.colorado.edu/~lindenle
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