[tulip] No Link Beat on Cable Modem

[Donald Becker]

On Tue, 27 Mar 2001, David wrote:

> I have an SMC 8432 (Tulip 21041-based) ethernet card and cable modem
> from AT&T of Colorado.  In Win95, they set a special option on the
> driver to tell it to not look for a link beat, since the cable modem box
> (RCA model DCM205) does not generate a link beat.

A correct 10baseT link partner must generate link beat.

>  When I boot Linux
> with the tulip driver, I get this:
> 
> kernel: eth0: No 21041 10baseT link beat, Media switched to 10base2.
> kernel: eth0: No 21041 10baseT link beat, Media switched to 10base2.

This is the correct behavior.

> When I try to force it to 10baseT (modprobe tulip options=12 debug=6),
> this is what I get:
> 
> tulip.c:v0.92t 1/15/2001  Written by Donald Becker <becker@scyld.com>
>   http://www.scyld.com/network/tulip.html
> eth0: Digital DC21041 Tulip rev 33 at 0xd0015000, 00:E0:29:61:67:16, IRQ
> 9.
> eth0: Transceiver selection forced to 10baseT(forced).
> eth0: 21041 Media table, default media 0800 (Autosense).
> eth0:  21041 media #0, 10baseT.
> eth0:  21041 media #4, 10baseT-FDX.
> eth0: tulip_open() irq 9.
> eth0: 21041 using media 10baseT, CSR12 is 00c4.
...
> eth0: Media selection tick, 10baseT(forced), status fc660000 mode
> fffe2002 SIA 000020c6 ffffef01 ffffffff ffff0008.
> eth0: 21041 media tick  CSR12 000020c6.
> eth0: Media selection tick, 10baseT(forced), status fc660000 mode
> fffe2002 SIA 000020c6 ffffef01 ffffffff ffff0008.
> 
> I can't ping anything, even the router.

This is the correct behavior.  The 21041 will not transmit unless it
sees 10baseT link beat.

This can be overridden by clearing CSR14 bit 12 (0x1000).

Please try the following:
   Change your media type to '3'  (options=3)
   Change line 477 as follows:

-static u16 t21041_csr14[] = { 0xFFFF, 0xF7FD, 0xF7FD, 0x7F3F, 0x7F3D, };
+static u16 t21041_csr14[] = { 0xFFFF, 0xF7FD, 0xF7FD, 0x6F3F, 0x7F3D, };


Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993