[tulip] stall on tulip card

[Dan Hollis]

On Tue, 9 Jan 2001, Donald Becker wrote:
> On Mon, 8 Jan 2001, Dan Hollis wrote:
> > Donald, I have about 10 data points now from people who have used the
> > CSR18 bit 1 patch. For most of them (9 out of 10) it fixed the problem
> > and for the last it didnt change anything, eg it didnt make things worse.
> Does this mask the TxUnderrun event?
> If so, the Tx threshold will never be increased, and the Tx underruns will
> continue.

It masks tx underrun totally. Once CSR18 bit 1 is set, the driver never
ever sees another tx underrun event (we never ever see TxFIFOUnderflow
once CSR18 is set).

BTW if we just ignore underrun and restart the transmitter on underflow
errors, the centaur will get totally locked up. If we bump up the
threshold and restart, it may delay it a while, but we will still
eventually get locked up.

Whatever magic this CSR18 bit does, it totally compensates at a hardware
level for these problems. I wish ADMtek would actually tell us what the
hell it is doing.

-Dan