Summary

On an Orange Pi 5 Pro with the onboard AP6256 / BCM43456 module, the default brcmfmac path on ubuntu-rockchip was unstable in real hardware testing, while switching the board to bcmdhd-sdio made 5 GHz stable again.

This is related to but more detailed than the older closed report in #841.

Environment

• Board: Orange Pi 5 Pro
• Wi-Fi module: AP6256 / BCM43456 (SDIO)
• OS: Ubuntu 24.04.1 LTS
• Kernel: 6.1.0-1025-rockchip
• Repo/image family: Joshua-Riek/ubuntu-rockchip
• Verified on hardware: 2026-04-12

Failure modes seen on the default path

With the board using the default brcmfmac path:

1. Sometimes the Wi-Fi device failed during boot:
   • brcmf_attach: dongle is not responding: err=-52
   • brcmf_sdio_firmware_callback: brcmf_attach failed
2. Other times 5 GHz came up briefly after boot, then disappeared after tens of seconds to a few minutes.
3. In the unstable case, the board would effectively fall back to 2.4 GHz visibility only, and connectivity would drop.

Representative boot log from the failing brcmfmac path:

brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43456-sdio for chip BCM4345/9
ieee80211 phy0: brcmf_bus_started: failed: -52
ieee80211 phy0: brcmf_attach: dongle is not responding: err=-52
brcmfmac: brcmf_sdio_firmware_callback: brcmf_attach failed

What was tested

The following did not fix the root problem:

• replacing brcmfmac43456-sdio.bin
• replacing brcmfmac43456-sdio.txt
• removing / changing the clm_blob
• NetworkManager / wpa_supplicant level workarounds

The firmware bin/txt matched the official Orange Pi image, so this did not look like a simple wrong-firmware-file problem.

What did fix it

Switching the board to the Broadcom BCMDHD SDIO path fixed the issue in repeated testing:

• install bcmdhd-sdio-dkms
• blacklist brcmfmac / brcmutil for this board
• use the BCMDHD firmware / NVRAM / config paths explicitly
• power the SDIO Wi-Fi module down cleanly on shutdown / reboot

Validation after the fix

After switching to bcmdhd_sdio, the board repeatedly connected and stayed on 5 GHz:

• SSID: CMCC-201-5G
• BSSID: 48:81:d4:89:db:3f
• frequency: 5180 MHz / channel 36 / 80 MHz environment
• driver path: bcmdhd_sdio + dhd_static_buf_sdio

This remained stable past the old failure window after:

• cold boot
• warm reboot

Representative successful log:

wl_android_wifi_on : Success
wl_iw_event : Link UP with 48:81:d4:89:db:3f
wl_bss_connect_done : Report connect result - connection succeeded

Proposed fix

I opened PR #1343 with the board-level change that matched the successful hardware validation:

• install bcmdhd-sdio-dkms for Orange Pi 5 Pro
• stop using the brcmfmac path for this board
• replace the old reboot-only brcmfmac unbind helper with a shutdown/reboot poweroff helper

PR: #1343

If useful, I can also add a follow-up comment with full before/after command output from the live board.