Subject: Re: SMC Power155 ATM versus en driver
To: None <>
From: Chuck Cranor <>
List: current-users
Date: 10/10/2001 20:47:38
In article <>,
Michael K. Sanders <> wrote:
>I have a couple SMC Power155 PCI ATM cards, which are apparently just
>OEM versions of the Efficient card.  I played with them a few years ago
>and I believe they probed just fine, though I never actually used them.
>Now, however, something isn't working.
>en0 at pci0 dev 11 function 0: Efficent Networks 155P-MF1 ATM (ASIC) (rev. 0x00)
>en0: interrupting at irq 10
>en0: unexpected timeout in tx DMA test
>en0: unexpected timeout in tx DMA test
>en0: WARNING: WMAYBE DMA test failed 56 time(s)
>en0: ATM midway v0, board IDs 6.0, Utopia (pipelined), 512KB on-board RAM
>en0: maximum DMA burst length = 64 bytes (must align)
>en0: 7 32KB receive buffers, 8 32KB transmit buffers allocated
>en0: End Station Identifier (mac address) 00:00:c0:44:61:e0

>Any ideas?

when the driver attaches to an "en" it does a whole bunch of
test DMA operations to see what your system supports.   some
motherboards fail in such a way that it causes an 
"unexpected timeout in tx DMA test" error on some tests.

once the driver finishes the tests it imposes a set of DMA
restrictions so that only known-good DMA operations are used.
in your case it concluded:
	en0: maximum DMA burst length = 64 bytes (must align)

64 is the max burst size, but your system only allows it if
the starting address is on a 64-byte aligned boundary (that's
the "must align" restriction).    

the driver may have to do extra DMA operations to meet this 
restriction, but after autoconfig it should (in theory) work