vc4.ko causes another misterious error

[Ryutaroh Matsumoto]

Hi Stefan, thanks again for your response.

> sorry, this error description isn't helpful. Wifi especially 802.11ac
> has a little bit more than a simple on/off switch.

I recheck the situation with Debian kernel 5.10.24 and
Debian firmware-brcm80211 20201218-3.
5GHz WiFi works fine with vc4 and without vc4.

With vc4 loaded, I still have a mysterious error message
[   60.383011] mmc1: Timeout waiting for hardware cmd interrupt.
[   60.383030] mmc1: sdhci: ============ SDHCI REGISTER DUMP ===========
[   60.383035] mmc1: sdhci: Sys addr:  0x00000000 | Version:  0x00001002
[   60.383097] mmc1: sdhci: Blk size:  0x00000000 | Blk cnt:  0x00000000
[   60.383106] mmc1: sdhci: Argument:  0x00000000 | Trn mode: 0x00000000
[   60.383113] mmc1: sdhci: Present:   0x1fff0001 | Host ctl: 0x00000001
[   60.383120] mmc1: sdhci: Power:     0x0000000f | Blk gap:  0x00000080
[   60.383126] mmc1: sdhci: Wake-up:   0x00000000 | Clock:    0x0000f447
[   60.383132] mmc1: sdhci: Timeout:   0x00000000 | Int stat: 0x00000000
[   60.383138] mmc1: sdhci: Int enab:  0x00ff1003 | Sig enab: 0x00ff1003
[   60.383144] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00000000
[   60.383149] mmc1: sdhci: Caps:      0x45ee6432 | Caps_1:   0x0000a525
[   60.383156] mmc1: sdhci: Cmd:       0x0000371a | Max curr: 0x00080008
[   60.383162] mmc1: sdhci: Resp[0]:   0x00000000 | Resp[1]:  0x00000000
[   60.383168] mmc1: sdhci: Resp[2]:   0x00000000 | Resp[3]:  0x00000000
[   60.383173] mmc1: sdhci: Host ctl2: 0x00000000
[   60.383178] mmc1: sdhci: ADMA Err:  0x00000000 | ADMA Ptr: 0x00000000
[   60.383183] mmc1: sdhci: ============================================

The above message disappears with blacklisting vc4.ko or
by inserting an SD card to the SD card slot.

Debian package of firmware-brcm80211 newer than 20201218-3
has a severe issue with 5GHz WiFi as reported at
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=984489
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=985632
But it is a separate topic.

Best regards, Ryutaroh