Missing brcmfmac43456 Firmware for Raspberry Pi 400 in OpenWrt (openwrt-24.10.0-rc7-bcm27xx-bcm2711-rpi-4-ext4-factory.img.gz)

[linpf]

Description:
The Raspberry Pi 400 uses the brcmfmac43456 Wi-Fi chipset, but OpenWrt does not include the required firmware files (brcmfmac43456-sdio.bin and related files). As a result, the wireless interface is missing, and users see "firmware not found" errors in dmesg.

Manually copying the firmware from Raspberry Pi OS (Raspbian) to /lib/firmware/brcm/ resolves the issue, confirming that OpenWrt's firmware package is incomplete.

Steps to Reproduce:
Install openwrt-24.10.0-rc7-bcm27xx-bcm2711-rpi-4-ext4-factory.img.gz (or mainline) on a Raspberry Pi 400.
Boot OpenWrt and check the kernel logs:
sh
Copy
Edit
dmesg | grep brcm
The following error appears:
vbnet
Copy
Edit
brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43456-sdio.bin
brcmfmac: brcmf_fw_alloc_request: firmware not found
No wireless interface is available (iw dev shows no output).
Expected Behavior:
OpenWrt should include brcmfmac43456-sdio.bin in its firmware package so that the Raspberry Pi 400's Wi-Fi works out of the box.

Workaround:
Manually copying the firmware from Raspberry Pi OS to /lib/firmware/brcm/ fixes the issue:

sh
Copy
Edit
cd /lib/firmware/brcm/
wget https://github.com/RPi-Distro/firmware-nonfree/raw/master/brcm/brcmfmac43456-sdio.bin
wget https://github.com/RPi-Distro/firmware-nonfree/raw/master/brcm/brcmfmac43456-sdio.clm_blob
wget https://github.com/RPi-Distro/firmware-nonfree/raw/master/brcm/brcmfmac43456-sdio.txt
sync
reboot
After reboot, Wi-Fi works as expected.

Proposed Fix:
Include brcmfmac43456-sdio.bin, brcmfmac43456-sdio.txt, and brcmfmac43456-sdio.clm_blob in the firmware-brcmfmac package.
Verify that OpenWrt detects the Raspberry Pi 400 correctly and loads the appropriate firmware.
System Information:
Device: Raspberry Pi 400
OpenWrt Version: 23.05.0-rc7 (also tested with mainline OpenWrt)
Kernel Log Output: "firmware not found" for brcmfmac43456
Additional Notes:
This issue does not occur in Raspberry Pi OS, as it includes the correct firmware files. Adding these files to OpenWrt will ensure Wi-Fi functionality for Raspberry Pi 400 users.