v5.4.18 backports fmac driver fails to load when used on 4.9 kernel

[ApNa_2097886]

Hi ,

We recently tried to upgrade our 4.14.77 backports fmac driver to the latest 5.4.18 backports version.

The 4.14.77 backports was also being run on the 4.9 linux kernel and was working fine.

However when we tried to load the 5.4.18 package on the 4.9 kernel it fails with the highlighted error.

We have applied all the kernel configs suggested in the cypress readme so the build is successful but the driver load fails. See below.

How can we get past this issue?

07/06/20 10:46:43.851405 kern.inf kernel: Backport generated by backports.git v5.5.11-1-0-gabe05f0

07/06/20 10:46:43.861284 kern.not kernel: cfg80211: Loading compiled-in X.509 certificates for regulatory database

07/06/20 10:46:43.871289 kern.not kernel: cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'

Wland restarted. Pls wait...

07/06/20 10:46:43.931298 kern.inf kernel: brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43455-sdio for chip BCM4345/6

07/06/20 10:46:43.931400 kern.inf kernel: usbcore: registered new interface driver brcmfmac

07/06/20 10:46:43.931430 kern.war kernel: brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.fsl,imx7d-sdb.txt failed with error -2

07/06/20 10:46:43.931468 kern.war kernel: brcmfmac mmc1:0001:1: Falling back to user helper

Thanks and regards,

Aparna

[ErBe_1728341]

What happens next in dmsg?

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[yasa_4608926 · Accepted solution]

Hi,

For nvram files are board-specific, first request will be tried using a board-specific path.

If it fails, second request will be tried without a board-specific path.

see brcmf_fw_request_firmware() in drivers/net/wireless/broadcom/brcm80211/brcmfmac/firmware.c.

I think that this is not really an "error".

If it fails to load the kernel modules, there may be other causes.

For fmac debugging, see FMAC Debugging .

Best regards,

Yasa