Linux-firmware for Realtek rtl8192cu wifi dongle

Dear
I’m using buildroot to build a custom root file system for BeagleBone. My application uses a wifi dongle (Realtek 8192 chipset). I rebuilt kernel image (ver 3.2.0) and the image and wifi dongle work well with Debian root file system. My problem is : the built buildroot root file system get firmware error when modprobe rtl8192cu:

modprobe rtl8192cu

[ 194.077442] cfg80211: Calling CRDA to update world regulatory domain
Feb 15 08:01:23 beaglebone kern.info kernel: [ 194.077442] cfg80211: Calling CRDA to update world regulatory domain
[ 194.171603] rtl8192cu: MAC address: 00:0f:13:59:0f:e1
[ 194.176981] rtl8192cu: Board Type 0
Feb 15 08:01:23 beaglebone kern.info kernel: [ 194.171603] rtl8192cu: MAC address: 00:0f:13:59:0f:e1
Feb 15 08:01:23 beaglebone kern.info kernel: [ 194.176981] rtl8192cu: Board Type 0
[ 255.203972] usbcore: registered new interface driver rtl8192cu

Feb 15 08:02:24 beaglebone kern.debug kernel: [ 255.203643] rtl8192cu:rtl92cu_init_sw_vars():<0-0> Failed to request firmware!

Feb 15 08:02:24 beaglebone kern.debug kernel: [ 255.203668] rtlwifi:rtl_usb_probe():<0-0> Can’t init_sw_vars.
Feb 15 08:02:24 beaglebone kern.info kernel: [ 255.203972] usbcore: registered new interface driver rtl8192cu

I also chose the option: Target packages → Hardware handling → Frimware → wifi firmware:
[ ] Marvell Wifi-Ex SD 8787
[ ] Ralink rt2501/rt61
[ ] Ralink rt73
[ ] Ralink rt27xx/rt28xx/rt30xx
[] Realtek 81xx
[
] Realtek 87xx
[] Realtek 88xx
[
] TI wl127x
[*] TI wl128x
[ ] TI wl18xx
But it can not change the error
Please help me
Thank you

Have you checked if you have the following firmware files:

/lib/firmware/rtlwifi/rtl8192cufw.bin
/lib/firmware/rtlwifi/rtl8192cufw_A.bin

/lib/firmware/rtlwifi/rtl8192cufw_B.bin

/lib/firmware/rtlwifi/rtl8192cufw_TMSC.bin

It is also possible to modify the driver to bypass firmware loading for that chipset and it will work just fine. (I have done it before)