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Fingerprint sensor stops working after adding fingerprint

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asked 2018-06-12 22:31:24 +0300

mirumger gravatar image

updated 2018-06-12 23:02:06 +0300

objectifnul gravatar image

I had already stored five different Fingerprints, when I tried to add 6th one I got the error message "Your fingerprint couldn't be captured". In the menu I have the choice of retry or cancel. After selecting retry the same error message occurs. By choosing retry once or several times it looks like the fingerprint will be captured, but it never succeed. If the device is locked afterwards it cannot be unlocked by fingerprint.

So is it possible to capture more than 5 Fingerprints? If there is a limitation on 5 Fingerprints it would be great get a hint for that in settings.

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

spiiroin gravatar image

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

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.

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answered 2018-06-12 22:41:57 +0300

Spark gravatar image

updated 2018-06-12 22:42:42 +0300

5 fingerprints is the limit. I don't know the exact reason, but the Android Xperia X also has it, so I guess it is somewhere deeper in the system. I agree it would be nice to have a hint. Write it to @spiiroin, he may add it to the internal ticket of Jolla on fingerprint sensor improvements.

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Asked: 2018-06-12 22:31:24 +0300

Seen: 483 times

Last updated: Jun 13 '18