Hi once again !
I finaly found the solution :
When you use the kernel from digi/dey, they have activated the "user helper" (CONFIG_FW_LOADER_USER_HELPER)
When you load the wlan module, it will look for an inexistant qsetup30.bin firmware.
When the kernel fails to load the firmware, it asks the userspace helper (usually udev, but any equivalent would fit).
If this helper does not find the firmware, then the module loading goes on, and succeeds.
But if you don't have a "user helper" in your rootfs, then the module fails to load !!!
You can thus either (depending on your configuration and/or needs) :
- remove the user helper config from your kernel, - provide a user helper,
- modify the wlan driver so it goes on when there is no user helper, as it would when the firmware is not present !
Hope this will help