Re: PCI bus master with Prism2.5 (was: High CPU utilization of hostap)

From: John D. Rowell (
Date: 2002-05-07 01:11:19 UTC

Way to go Jouni :)

Any chance that there's a better way of doing this in hostap_cs also? Or, are there any cardbus prism2 around? My understanding is that cardbus is very similar to PCI.


On Monday, May 6, 2002, at 11:42 AM, Jouni Malinen wrote:

> On Sun, May 05, 2002 at 06:14:05PM +0300, Jouni Malinen wrote:
>> Data copying should be offloaded to
>> something other than CPU doing in/out loop. I'm not sure whether this
>> can be done without extra hardware. Prism2.5 PCI cards might have
>> better change of using DMA or bus master or something..
> It looks like this can be done on Prism2.5 PCI cards. However, it is
> more or less undocumented and unsupported.. After some guesses and
> testing, I managed to find (apparently ;-) proper control bits for
> reading and writing data from BAPs using bus master (i.e., driver just
> gives a memory address to the Prism2.5 and asks it to move N words of
> data from/to BAP to/from memory). I would assume that this would be a
> great performance improvement as far as host CPU is considered.

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