Fingerprint sensor stops working after adding fingerprint

answered 2018-06-13 07:49:56 +0300

spiiroin
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Short version is: "Xperia X fingerprint hal can deal with up to 5 fingerprints."

By default sailfish fingerprint software allows unlimited number of fingerprints. If underlying hal has somekind of hard limit / it starts misbehaving after N registered fingerprints, the number of allowed fingerprints is capped via device specific config files to some amount that is known to work.

In case of Xperia X it is: /etc/sailfish-fpd/50-settings-f5121.ini - where the relevant part is

[fpslave]
:
fphal_max_fingerprints_quirk    = 5
:

You can experiment (at your own risk etc) with larger values, by doing something like below as root:

printf > /etc/sailfish-fpd/90-myhacks.ini "[fpslave]\nfphal_max_fingerprints_quirk = 12\n"
systemctl restart sailfish-fpd

Then when you notice that it does not work any better, back to defaults via:

rm /etc/sailfish-fpd/90-myhacks.ini
systemctl restart sailfish-fpd

IIRC what happens in the case of Xperia X is: The hal rejects fingerprints in excess of 5, but only after otherwise successful acquisition -> What the config does is: It effectively makes the operation fail before the user has spend time on an action that has no chances of succeeding.