UDFPS on lockscreen UI partially active when fingerprint unlock disabled

[lbdroid]

I have set System Settings --> System --> Gestures --> "Tap to check phone" set to OFF. I also enable Always on Display: System Settings --> Display --> Lock screen --> "Always show time and info". Further, I have DISABLED fingerprint unlocking: System Settings --> Security --> Fingerprint

Problem: When the AoD is showing, if I touch the screen where the fingerprint sensor is, it reacts to the touch with haptic feedback, and it shows the unlock screen (pin). The unlock screen may or may not respond to touch input, except again over the fingerprint sensor (between the 8 and 0 keys). Tapping that area a few times will eventually enable touch input on the unlock screen.

No part of the screen should be sensitive to touch input while AoD is showing unless "Tap to check phone" is enabled.

[flawedworld]

I cannot reproduce this, please provide more information.

[lbdroid]

Interesting. What kind of information would you like?

[flawedworld]

We need to be able to reproduce this on a device or else we cannot help.

[lbdroid]

I understand that. I mean what information would help you do that?

[lbdroid]

I have some more information; If I ENTIRELY DELETE all fingerprints, then the problem disappears. If I add a fingerprint back, the problem comes back.

When there is a fingerprint added to the system, it shows a lock icon over the fingerprint sensor location on the AoD. When there are no fingerprints added, it does not show the lock icon (it is still locked by pin).

But like I said in the original message, I have it set to disable fingerprint unlocking.

If I recall correctly, AOSP/factory does NOT provide the ability to disable fingerprint unlocking if a fingerprint is added, rather that is a GrapheneOS feature. I suspect that the fingerprint unlock is not being fully disabled.

[flawedworld]

It sounds like the code path within AOSP for under display fingerprint is checking for biometric unlocking support in an odd way.

[lbdroid]

Thinking about this more, the intended behavior of upstream is probably relevant in this circumstance;

In upstream builds where there is no option to disable fingerprint unlocking, when fingerprint and AoD are both enabled, you would place your finger on the reader part of the screen, and it would go through the full wake up and unlock cycle without any further input. I.e., no need to first wake it up and then unlock it, just put your finger on that part of the screen and it goes through the whole process.

If fingerprint unlocking is NOT enabled, but AoD is, then it won't have that sensitivity over the fingerprint.

So I would say that the "upstream" label is probably not appropriate here, since upstream works as intended. The issue is a result of the GrapheneOS exclusive feature that allows fingerprint security but not unlocking.

[thestinger]

Disabling fingerprint unlock is supported upstream, just not in the Settings UI.

[lbdroid]

Ok. I thought it was all or nothing.