Re: eepro100 vs. ntulip speed

[Marty Connor <mdc@thinguin.org>]

On 2/21/2000 2:53 AM Bob Edwards Robert.Edwards@anu.edu.au wrote:

> - ntulip_transmit doesn't need to stop and start the transmitter for
>	each frame

Be very careful here.  The DECchip 21041 PCI Ethernet LAN Controller 
Hardware Reference Manual states that   "Writing to either CSR3 or CSR4 
is permitted only when its respective process is in the stopped state."   
 

I did some testing and debugging, and this turned out to be what was 
causing the LC82C168 based card (NetGear FA310TX) to hang using your 
patch.  ntulip_transmit stops TX in order to write to CSR4.  It appears 
some cards don't mind if you touch this register while the TX process is 
running, but since there is no conditionalization in the ntulip_transmit 
routing, it is unsafe.  

Please pass this along to Paul Mackerras of Linuxcare's OZLabs.

Regards,

Marty

---
   Name: Martin D. Connor
US Mail: Entity Cyber, Inc.; P.O. Box 391827; Cambridge, MA 02139; USA
  Voice: (617) 491-6935, Fax: (617) 491-7046 
  Email: mdc@thinguin.org
    Web: http://www.thinguin.org/


===========================================================================
This Mail was sent to netboot mailing list by:
Marty Connor <mdc@thinguin.org>
To get help about this list, send a mail with 'help' as the only string in
it's body to majordomo@baghira.han.de. If you have problems with this list,
send a mail to netboot-owner@baghira.han.de.