[vortex] 3C905CX, 2.2.18, Dell Dimension 4100 (P933) ReceiveFailure Fix / Inquiry

[Donald Becker]

On Wed, 17 Jan 2001, Joe Rouvier wrote:
> Donald Becker wrote:

> > Most of the operations should take zero apparent time.  I check the loop
> > count for all operations when I write a driver, and it's rare that a
> > chip actually requires more than one loop iteration.
> 
> If it's rare for a device to take more than one PCI transaction to do
> something, do you think the ~30000 transaction count for RxReset on the
> 3c905cx means the current driver doesn't init the card correctly?  Or is
> the new chip just slow on that command?

My _guess_ is some designer took the easy way out when writing the
internal firmware.  Rather than reset the receive logic, they just
turned off the reciever and started a timing loop that would be long
enough to be certain that the chip was no longer active.

> But the longer loop is only used on TxReset, RxReset, TotalReset,
> DownStall and RxDiscard.  Aren't these commands sent very rarely?
> (referring specifically to the 2.2.19-pre2 driver with Adam M's
> wait_for_completion() changes)

They might be rare in some usage, but not in all.  A machine that
does ifdown eth0; <change something>; ifup eth0 would see the long delay
very frequently.

> I don't suppose anyone has heard anything from 3com?

Just that it will be several weeks before the manual is available.

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