Path: utzoo!attcan!uunet!mcsun!sunic!nuug!ifi!arneme
From: arneme@sfd.uit.no (Arne Munch-Ellingsen)
Newsgroups: comp.arch
Subject: Am7990 LANCE chip
Message-ID: <2496@ifi.uio.no>
Date: 12 Jan 90 16:21:48 GMT
Sender: news@ifi.uio.no
Reply-To: arneme@sfd.uit.no (Arne Munch-Ellingsen)
Organization: University of Tromsoe, Norway
Lines: 33

I am trying to write a device driver for the Am 7990 LANCE chip. The driver
is going to be a part of a small standalone kernel for the MC68030. The on
board (We are using the MVME 147 boards) MC68851 MMU is not activated.

After setting up the exeption/trap vectors, initiating the tick timer 1 to
give interrupts at a 10 HZ rate at level 6 the LANCE itself is initialized.

The mode part of the initialization block is set to 0x0000, the physical
adress is set to my address which is 8:0:3E:20:1:99. The logical adress
filter is set to all zeros, and the Receive Descriptor Ring Pointer (RDRP)
(bits 0-23) is set to the adress of the first of 8 receive descriptors
allocated contigiously in memory. (the rlen part of the RDRP is set to
0x3). The TRDP is set accordingly (also have 8 transmit descriptors). RMD0 and
RMD1 is set to reflect the address where the receive descriptors are, and
the OWN bit is set to 0. RMD2 (bcnt) is set to -1518. TMD0 and TMD1 is set
to the address of the transmit descriptor entries.

Everything seems to work fine, but the LANCE misses all packets. By
toggling the PROMISCIOUS bit I can verify that the initblock address the
LANCE is using is OK. (number of interrupts generated indicates this)

According to the documentation the MISS error should only occur if the
LANCE doesn't own any buffers. I have inspected the DMA area in detail, and
everything seems to be OK (right offset from the start, and correctly
initialized)

Have I overlooked some crusial detail ??

Arne Munch-Ellingsen (arneme@sfd.uit.no)
 ____________________________________________________________
|     Arne Munch-Ellingsen                                   |
|     Department of Computer Science, University of Tromsoe  |
|     Postboks 953, N-9000 TROMSOE, NORWAY.                  |