Hi, i'm working in a project that is using madwifi driver. We need to change the channel bandwidth, but we saw that there isn't a iwpriv command that do this. So, we began to code the new comand.
After studing the driver, we saw that CHANNEL_HALF and CHANNEL_QUARTER  should do the thing. I get the last driver on the branch svn, with Hal
To test this feature, i forced the flags in function ath_chan_set. I did this:

hchan.channelFlags |= CHANNEL_HALF;

But when the driver calls ath_hal_reset, passing this hchan, this error occurs:

wifi0: ath_chan_set: unable to reset channel 11 (2462 Mhz) flags 0x40c0 'Invalid parameter to function' (HAL status 12)

Note that i'm working in 2,4Ghz and i set the channel 11 in this example.

Somebody knows what i'm doing wrong? What i have to do to set the bandwidth?