Hi,

today i tested Linux 5.18-rc1 on my Raspberry Pi 400 connected to my
HDMI display (multi_v7_defconfig + CONFIG_ARM_LPAE, firmware:
2021-01-08T14:31:16) and i'm getting these strange errors from
raspberrypi-firmware driver / vc4 during boot:

[   13.094733] fb0: switching to vc4 from simple
[   13.110759] Console: switching to colour dummy device 80x30
[   13.120691] raspberrypi-firmware soc:firmware: Request 0x00030066
returned status 0x80000001
[   13.120715] vc4-drm gpu: [drm] Couldn't stop firmware display driver: -22
[   13.120839] vc4-drm gpu: bound fe400000.hvs (ops vc4_hvs_ops [vc4])
[   13.121213] Bluetooth: Core ver 2.22
[   13.121266] NET: Registered PF_BLUETOOTH protocol family
[   13.121270] Bluetooth: HCI device and connection manager initialized
[   13.121281] Bluetooth: HCI socket layer initialized
[   13.121286] Bluetooth: L2CAP socket layer initialized
[   13.121297] Bluetooth: SCO socket layer initialized
[   13.132879] cfg80211: Loading compiled-in X.509 certificates for
regulatory database
[   13.164278] Bluetooth: HCI UART driver ver 2.3
[   13.164293] Bluetooth: HCI UART protocol H4 registered
[   13.166608] raspberrypi-firmware soc:firmware: Request 0x00030066
returned status 0x80000001
[   13.166633] vc4-drm gpu: [drm] Couldn't stop firmware display driver: -22
[   13.166717] vc4-drm gpu: bound fe400000.hvs (ops vc4_drm_unregister
[vc4])
[   13.176173] Bluetooth: HCI UART protocol Broadcom registered
[   13.182365] hci_uart_bcm serial0-0: supply vbat not found, using
dummy regulator
[   13.182505] hci_uart_bcm serial0-0: supply vddio not found, using
dummy regulator
[   13.300636] uart-pl011 fe201000.serial: no DMA platform data
[   13.422683] raspberrypi-firmware soc:firmware: Request 0x00030066
returned status 0x80000001
[   13.422700] vc4-drm gpu: [drm] Couldn't stop firmware display driver: -22
[   13.422788] vc4-drm gpu: bound fe400000.hvs (ops vc4_drm_unregister
[vc4])
[   13.458620] bcmgenet fd580000.ethernet: GENET 5.0 EPHY: 0x0000
[   13.461925] raspberrypi-firmware soc:firmware: Request 0x00030066
returned status 0x80000001
[   13.461941] vc4-drm gpu: [drm] Couldn't stop firmware display driver: -22
[   13.462006] vc4-drm gpu: bound fe400000.hvs (ops vc4_drm_unregister
[vc4])
[   13.469287] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[   13.507497] vc4-drm gpu: bound fef00700.hdmi (ops vc4_drm_unregister
[vc4])
[   13.521840] brcmfmac: brcmf_fw_alloc_request: using
brcm/brcmfmac43456-sdio for chip BCM4345/9
[   13.522128] brcmfmac mmc0:0001:1: Direct firmware load for
brcm/brcmfmac43456-sdio.raspberrypi,400.bin failed with error -2
[   13.535444] brcmfmac mmc0:0001:1: Direct firmware load for
brcm/brcmfmac43456-sdio.raspberrypi,400.txt failed with error -2
[   13.564153] Bluetooth: hci0: BCM: chip id 130
[   13.564675] Bluetooth: hci0: BCM: features 0x0f
[   13.566157] Bluetooth: hci0: BCM4345C5
[   13.566164] Bluetooth: hci0: BCM4345C5 (003.006.006) build 0000
[   13.568434] Bluetooth: hci0: BCM4345C5 'brcm/BCM4345C5.hcd' Patch
[   13.570485] unimac-mdio unimac-mdio.-19: Broadcom UniMAC MDIO bus
[   13.576820] vc4-drm gpu: bound fef05700.hdmi (ops vc4_drm_unregister
[vc4])
[   13.576967] vc4-drm gpu: bound fe004000.txp (ops vc4_drm_unregister
[vc4])
[   13.577044] vc4-drm gpu: bound fe206000.pixelvalve (ops
vc4_drm_unregister [vc4])
[   13.577118] vc4-drm gpu: bound fe207000.pixelvalve (ops
vc4_drm_unregister [vc4])
[   13.577185] vc4-drm gpu: bound fe20a000.pixelvalve (ops
vc4_drm_unregister [vc4])
[   13.577237] vc4-drm gpu: bound fe216000.pixelvalve (ops
vc4_drm_unregister [vc4])
[   13.613504] [drm] Initialized vc4 0.0.0 20140616 for gpu on minor 0

Best regards