wifi dies if i switch console while downloading

[A65]

If I start a download using curl (in a tty) or firefox, then switch consoles using ctrl-alt-X or alt-X, the following messages show up in syslog and the wireless connection fails.

Mar  1 17:48:58 <host> dhcpcd[18211]: wlan0: carrier lost
Mar  1 17:48:58 <host> kernel: No probe response from AP 00:11:22:22:11:11 after 500ms, disconnecting.
Mar  1 17:48:58 <host> kernel: cfg80211: Calling CRDA to update world regulatory domain

I can switch consoles with no problems while browsing or with irc open, but when downloading it causes this problem.

Also, I use radeondrmfb. Because this is a 64-bit powerpc machine (out of the norm hardware), I think it is possible that a "hiccup" is occurring at the kernel level when radeondrmfb is handling the console switch, and that is causing/preventing whatever manages the wireless card to fail to process any AP probe responses, leading to the kernel seeing no response and disassociating. could this be possible? I have rebuilt a kernel with verbose printk of the syslog "no probe response" message shown above, and am going to test it tomorrow.

thanks for your help

[A65]

I've found loading b43 with pio=1 prevents this problem. I have two questions though.

1) How do I get the kernel to load b43 with pio=1? The module is not being loaded by any of my init scripts, can I use b43.pio=1 as a kernel argument?
2) I read PIO is slow and will bog down the cpu. top is showing 17% cpu usage now for irq/60-b43. How do I get DMA to work right with this wireless card?