Enabling the m64 eMMC under armbian

The m64 eMMC is not showing up under armbian (5.4.43-sunxi64). Here is the relevant bits of dmesg’s output:

gollumm64% dmesg | grep mmc | less -X
[    4.149531] sunxi-mmc 1c0f000.mmc: Got CD GPIO
[    4.173403] sunxi-mmc 1c0f000.mmc: initialized, max. request size: 16384 KB, uses new timings mode
[    4.174864] sunxi-mmc 1c10000.mmc: allocated mmc-pwrseq
[    4.198553] sunxi-mmc 1c10000.mmc: initialized, max. request size: 16384 KB, uses new timings mode
[    4.212933] mmc0: new high speed SDHC card at address aaaa
[    4.214519] mmcblk0: mmc0:aaaa SC32G 29.7 GiB 
[    4.218980]  mmcblk0: p1
[    4.225348] sunxi-mmc 1c11000.mmc: initialized, max. request size: 2048 KB, uses new timings mode
[    4.230854] mmc1: queuing unknown CIS tuple 0x80 (2 bytes)
[    4.232411] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    4.233952] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[    4.236706] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)
[    4.240057] mmc1: queuing unknown CIS tuple 0x81 (9 bytes)
[    4.326461] mmc2: error -110 whilst initialising MMC card
[    4.331144] mmc1: new high speed SDIO card at address 0001
[    9.205905] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43430-sdio.sinovoip,bananapi-m64.txt failed with error -2

I think the eMMC is mmc2, but it appears to be getting a timeout for some reason. What do I need to do to get mmcblk1 to show up under /dev?