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

[Jerry Van Baren <gvb.uboot@gmail.com>]

Hi Loren,

Please don't top post.  It annoys us curmudgeons.

Loren A. Linden Levy wrote:
> Hi All,
> 
> I still have not found a solution and I am a bit desperate. I did not
> seem to be able to send any packets (using ping) from the FECO on the
> M5282Lite board to the tftp host, however pings from the host were
> answered and I saw packets going from the coldfire board to the host
> in wireshark. I also get a strange error when I ask for mii info:
> 
> uBOOT=>> mii device
> MII devices: 'FEC0' 
> Current device: 'FEC0
> 
> uBOOT=>> mii info
> MII not complete
> MII not complete
> ...
> 
> a dump gives me:
> 
> 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)

Note that ALL the bits are '1'.  That is indicating your PHY is NOT 
DRIVING data on the MII data line (always idle high).  Odds are really 
good that you are not driving your MII clock and data properly, your PHY 
isn't at the address you think it is at, or your hardware has problems. 
  The only reason you are getting any ether activity is likely because 
your PHY is defaulting to a configuration that is mostly (not entirely) 
broken.

* Double-check your MII clock and data pin configurations.  Are you 
initializing them correctly?  Error probability: 87%.

* What address is your PHY strapped to?  You need to know this.  Error 
probability: 11% (your emails imply you don't know this - I bumped the 
probability up because of that impression).

* Use a logic analyzer (preferred), o-scope (good) or a logic probe on 
your PHY's MII clock and data lines and verify they are receiving the 
right sequence (or at least wiggling when you do the MII commands). 
With a logic analyzer you should be able to read the data you are 
sending and verify the bit pattern.  You can do this with an o-scope 
(especially a digital one) too, but a little trickier.  This is likely a 
software error (above 87% + 11%) - hardware error probability: 2%

* Oh yeah, you might be clocking the MII lines too fast.  Pretty small 
probability, though.

[snip]

Good luck and happy probing,
gvb

P.S. I used mostly odd percentages because I read somewhere that made up 
percentages are more believable when they are odd.  ;-)