PinePhone Keyboard won't work. read_kb_reg(PPKB_SYS_CONFIG) needs what?

[jovval]

As root, I did,
pacman -Syu
pacman -S git php sdcc make gcc
As a normal user I did,
git clone https://megous.com/git/pinephone-keyboard
cd pinephone-keyboard
make all

As root, I continued with
cp -a Downloads/pinephone-keyboard/build/* /usr/local/bin/
vi /etc/systemd/system/ppkb-i2c-inputd.service
and added,
[Unit]
Description=Pinephone Keyboard Service Daemon

[Service]
Type=simple
ExecStart=/usr/local/bin/ppkb-i2c-inputd

[Install]
WantedBy=multi-user.target

I had no need to blacklist kbd51
lsmod | grep kbd
gave nothing. I did see
pinephone_keyboard    16384  0
at the end of lsmod.
I enabled the new systemd service.
systemctl enable ppkb-i2c-inputd.service
Created symlink /etc/systemd/system/multi-user.target.wants/ppkb-i2c-inputd.service → /etc/systemd/system/ppkb-i2c-inputd.service.
The following did/showed nothing.
systemctl start ppkb-i2c-inputd
ps ax | grep ppkb
gave no match.
I rebooted and found the same results both above and below.

The following command (with the PPP out of and in the ppkb) generated a WARNING and an ERROR.
pkb-i2c-inputd
WARNING: I2C_RDWR failed (6)
ERROR: read_kb_reg(PPKB_SYS_CONFIG) failed: No such device or address

Having inserted the PPP into the ppkb, I found that charging works.
The keys do not work.
How may I obtain "such device or address"?