I can't enable power management functions on my Broadcom BCM4311 WLAN card (as sugested by PowerTOP) Here are some prints:
root@grumpy:~# lspci -vnn | grep 14e4 0c:00.0 Network controller : Broadcom Corporation BCM4311 802.11b/g WLAN [14e4:4311] (rev 01) root@grumpy:~# iwconfig lo no wireless extensions. eth0 no wireless extensions. wlan0 IEEE 802.11bg ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=20 dBm Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off root@grumpy:~# iwconfig wlan0 power on Error for wireless request "Set Power Management" (8B2C) : SET failed on device wlan0 ; Operation not supported.
The machine is Dell D420, running Ubuntu 11.10. I always had problems with my WiFi driver and currently use the package firmware-b43-installer, and manually load the b43 module.