Re: [PATCH take 2] Atmel MACB ethernet driver

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On Fri, 17 Nov 2006, Haavard Skinnemoen wrote:
> Hmm...underruns as in "eth0: TX underrun, resetting buffers"?

Yes, that's the message.

> (...)
> If it's a problem with the descriptor, it would probably help to dump
> out some information about the ring state, i.e. the value of
> bp->tx_head and bp->tx_tail, and maybe dump all outstanding descriptors
> in the ring to see if any of them look suspicious.

I've added some printk()s in underrun handler. There's still some data
in the ring (tail=29, head=32), so the driver seems okay. The list of

  tx_ring[28].ctrl=0x8000850e (used=1 wrap=0 und=0 last=1)
  tx_ring[29].ctrl=0x900085ea (used=1 wrap=0 und=1 last=1) TAIL
  tx_ring[30].ctrl=0x000085ea (used=0 wrap=0 und=0 last=1)
  tx_ring[31].ctrl=0x0000850e (used=0 wrap=0 und=0 last=1)
  tx_ring[32].ctrl=0x800085ea (used=1 wrap=0 und=0 last=1) HEAD
  tx_ring[33].ctrl=0x8000850e (used=1 wrap=0 und=0 last=1)

Buffer addresses look fine, tx_ring[29..32].addr don't differ much from
the rest. 

> If it's a bus latency issue, things start to get a bit
> platform-specific, so we should probably involve some more experienced
> ARM people.

Looks like I'll have to wait for upstream support of 9260, because I'm
new to ARM and I won't handle it by myself. Anyway thanks for your help.

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