[beagleboard-xm DSP usage] Loading module bridgedriver,but /dev/DspBridge now shown?

I worked with beagleboard-xm,and kernel 3.2(bluidroot).By enable Bridge driver in menuconfig,and rebuild kernel,I can load module successfully.

[root@beagleboard-xm ~]# modprobe mailbox     
[root@beagleboard-xm ~]# modprobe bridgedriver base_img=/lib/dsp/baseimage.dof 
[   53.080318] bridgedriver: module is from the staging directory, the quality is unknown, you have been warned.

But /dev/DspBridge now showing up. And when run dsp-probe and other dsp command, will cause “error: main: dsp open failed”

[root@beagleboard-xm ~]# dsp-probe 
error: main: failed to open DSP

Searching in google,I found some resource,but none of them work.
1. by dsp-bridge into kernel 2.6.33 : modprobe mailbox_mach first.
2. by Mailinglist Archive: opensuse-arm (109 mails): In kernel 3.4, module name changed to tidspbridge.

Is I missing some patch?
Is there more information output,such as dmesg….?