Fingerprint scanner issues when using Oled Saver - Redmi K20 / Xiaomi Mi 9T Questions & Answers

I am very sensitive to PWM. Since there is no Dc Mimming on our phone, I have to use different applications from the Play Store to eliminate screen flicker. They use a black translucent overlay to control the brightness of the screen. On MIUI, this works fine, I have not encountered any problems with this. But on custom firmware when using these applications, the fingerprint scanner does not work. You cannot even add a fingerprint. I am so assuming that on MIUI, all overlays are removed from the screen during fingerprint scanning and the reading mode is turned off due to which unlocking is successful, this is not provided for custom firmware. I hope that the developers will see it and fix it. Thanks!

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TWEAK/TIP - Prevent accidental unlocks

One of the big issues I have found, mainly with CM based ROMS, is that the option to prevent accidental unlocking seems to be missing/unavailable.
I've been testing various apps and utilities that monitor the proximity sensor, but there is one big issue - they monitor for screen on, but it seems in CM12.1 that the monitoring app doesn't work or get a screen on signal when you're using a lockscreen.
So the solution is not to check for screen on, but check for screen unlock.
I have a TASKER profile set up as follows:
If screen unlocked and proximity sensor on, then turn the screen off.
Works really simply. cover the proximity sensor with a bit of cloth or something and test it - if you double-tap the screen on, or it wakes due to a notification, the screen still goes on. But any subsequent action, eg slide to unlock or click on a notification, triggers the screen unlock flag, and this then checks to see if the proximity sensor is covered, and if it does, it turns the screen off again.
I CAN POST SCREENSHOTS IF ANYONE WANTS FURTHER INFO - BUT I'D SUGGEST GIVING TASKER A GO AND A PLAY ANYWAY, IT'S A BRILLIANT APP.

Screen flicker workaround

Hi everyone
I want to share a workaround to all of us who owns a defective S5
Symptom: You unlock your phone and it doesn't show anything. Actually, the phone is working. Capacitive buttons light up and you may heard some activity in the phone
Your phone has a defective screen. There are a lot S5 which have this problem, according to several forums. After several tries, unlock and lock over and over, the screen light up and you are able to use your phone. The problem is when you receive a call and you want to know who is calling you, the screen doesn't illuminate and you won’t be able to know who is.
Here's a workaround which makes your powerful S5 usable and take out from your drawer.
Solution:
The more effective way to fix it is: change defective screen! But sometimes it could cost as much as a new phone, or simply you can't afford it, and it's better to change your phone instead, and you put your S5 in a drawer.
The technical explanation of this problem is: Screen doesn't receive enough electrical current at low brightness levels (maybe the flex is defective, get old, etc)
Most probably the wake up problem exist together with screen flicker at low brightness levels
The wake up problem rises up more in dark environment, when light sensor make low bright screen
The lock screen light up screen, with a dim effect: when you lock the phone, it slowly turn screen off, and when you unlock, it make and effect of dim screen.
When you are is in dark environment, the effect is very slow, preventing the screen illuminate because the technical problem explained before.
When you are in very light environment, you lock screen and sensor light make the screen very brilliant and chances are you defective phone wakes up correctly.
We can use an app which give us complete control over brightness subsystem. I use an app called Velis AutoBrightness:
Once installed from Play Store, it shows a Setting Wizard. Follow the instructions. Below are some notes
• 1/7: Welcome Screen
• 2/7: How bright... Most probably is your phone always have flicker in low brightness. Choose "AMOLED" or "AMOLED bright". By the way choosing any one of those cure always minimum brightness failure!
• 3/7: Choose High sensitivity
• 4/7: On, if you want additional brightness when charging. Irrelevant for this thead. Choose your favorite setting
• 5/7: Same of 4/7
• 6/7: Choose enable: That enable the app
• 7/7: Some additional notes: Press Done
Now important settings: go to Menu > Settings > General: Settings Mode > Advanced
Service Activation settings:
• Disable system handler > ON: When you use Power saving mode, you surely noted screen flicker, which is very annoying, and make unusable power saving mode. By set this ON: Android doesn't set screen too dim; instead Velis have a minimum of brightness set by Wizard 2/7. (Surely you find out that you avoid screen flicker, by setting autobrightness off and slider in 8-10%)
Sensors settings:
• Screen-on sensor value override: Set this value to 30000. Read below this post if you want technical explanation of this setting
After you establish these settings, you'll be able to unlock your phone all the time!
This is the trick: When you unlock your phone, you'll note that the screen is very bright (because Screen-on to 30000) and quickly adjust to the environment light. The failure is that electrical current to screen is defective, and when exterior light is dark, the screen make a dim effect and doesn't light up.
Note to Marshmallow users:
• This app make use of Screen overlay permisions: And marshmallow is very restrict with this kind of app. This is specially true when you are installing an app. All you have to do is deactivate the app in notification screen: press "OFF" button, adjust system brightness upper enough to not flicker the screen, install your app, and activate Velis Autobrightness again
• Because of Doze mode, wake up from this mode may avoid your screen light up, the first time you use your phone. Let 10-15 seconds your phone wake up, lock again, and unlock again, and velis will make its work!
I hope this post make your smartphone usable. I barely apply this trick to two phones, but I think this is a good workaround!
I used this app & the flickering is still available
What worked for me is downgrading the firmware on my g900f all the way back to Android 4.0. My phone came with version 5.0 and I noticed the problem only after I kept installing samsung's system updates. Will report if the problem starts up again but I'm running rooted and running nougat just fine so I don't see a reason to keep upgrading the firmware.
Edit: nevermind, this didn't work
Reyse said:
The technical explanation of this problem is: Screen doesn't receive enough electrical current at low brightness levels (maybe the flex is defective, get old, etc)
Click to expand...
Click to collapse
Does anyone know for sure if it's the flex cable or some capacitors? I notice only the lower half of my screen flickers.. I bet there's a simple electrical fix for it instead of replacing the whoooole display
fbs said:
Does anyone know for sure if it's the flex cable or some capacitors? I notice only the lower half of my screen flickers.. I bet there's a simple electrical fix for it instead of replacing the whoooole display
Click to expand...
Click to collapse
Hello,
Have you change jour battery? If it s old it could cause some issues...
But try to buy a genuine one, I think that your battery must be old now.
Bye
cedouic said:
Hello,
Have you change jour battery? If it s old it could cause some issues...
But try to buy a genuine one, I think that your battery must be old now.
Bye
Click to expand...
Click to collapse
it doesn't make any sense. the lower half of the screen flickers in green even on charger
fbs said:
it doesn't make any sense. the lower half of the screen flickers in green even on charger
Click to expand...
Click to collapse
I noticed that screen only flickers at low brightness when using Boeffla kernel for LOS14 and others based on it.
No issue for the same device with LOS or Stock based kernels.
zlazaar said:
I noticed that screen only flickers at low brightness when using Boeffla kernel for LOS14 and others based on it.
No issue for the same device with LOS or Stock based kernels.
Click to expand...
Click to collapse
you're wrong
I was using los16 with stock kernel for months with flicker everyday
fbs said:
you're wrong
I was using los16 with stock kernel for months with flicker everyday
Click to expand...
Click to collapse
+1 to that , i even went back to stock and the screen flicker appeared and such issues are well known already with samsung amoled panels back in 2014-even some panels from 2018 . So def not kernel related.
I was using los 15.1 and this problem got worse. The phone was barely usable as mentioned by the op. In my case, the screen would start flickering below 60%. Then I switched back to stock marshmallow. I noticed that 100% brightness in los 15.1 is actually only about 70% in the stock rom.
I have been using the phone at 80% brightness for some weeks now and the problem has significantly reduced. But not completely gone, it's much much better. Also, you might want to avoid using dark wallpapers.

ZE552KL screen flickering at lowest brightness level

I would take a video of this issue, but I don't have a good enough camera. It's really, really hard to capture unless you have good video recording tech, which I don't have. :crying:
My issue is that, when I set the brightness to its lowest level on my Zenfone 3, the screen starts flickering. This is especially noticeable with white backgrounds. You can tell that the screen is flickering (perhaps refreshing?) rapidly and it makes the phone painful to look at.
Someone actually created a thread about this issue here on XDA a few months ago, with a video showing this issue, but unfortunately, the video doesn't capture the flickering properly. Here: https://forum.xda-developers.com/zenfone-3/help/ze520kl-low-screen-light-level-20-t3603502
How to reproduce:
-Turn auto-brightness off
-Slide brightness bar all the way to the left (AKA to the lowest level)
-Open a white background/grayish background or blank page in Chrome
-Screen starts flickering
It happens across the phone, and intermittently. Sometimes it happens, sometimes it doesn't. In Chrome, in games, whatever. I once thought it could be related to charging the phone, but the screen has flickered on low brightness even when my phone wasn't plugged in, and at 70-80% battery. I might try resetting the phone to see if it's a software defect; I really hope it is.
Turning off hardware overlays in Developer Options does not resolve this issue.
I'm currently on ASUS stock Nougat, unrooted. I can't root right now. I don't have any screen overlays apart from CF.Lumen, which isn't set to come on during the day, when the flickering happens, and I don't use any screen color modes apart from the default settings. I also always have auto-brightness turned off.
Just wondering if anyone else is having this issue. I might try recording it one day.
Thanks.
Update 1: Removed my 64GB SD Card from the phone to see if that made a difference. It didn't. So the flickering isn't related to power management, AFAIK.
Next step is to wipe the phone completely, including its cache partition from stock recovery, and set the phone up as new again. It might be a hardware issue, but my fingers are crossed.
I've had this issue since I got the phone, ZE552KL. Turning off auto brightness fixes it for me, so I have a feeling it has more to do with ASUS' auto brightness algorithms than anything else.
sensi277 said:
I've had this issue since I got the phone, ZE552KL. Turning off auto brightness fixes it for me, so I have a feeling it has more to do with ASUS' auto brightness algorithms than anything else.
Click to expand...
Click to collapse
I always have auto-brightness turned off. I think it might have to do with the ambient light sensor. I've tested it using SMMI and it works just fine. But I wish there was a way to disable it, since I don't need it. I'm kind of disappointed in this phone.
I'm going to try a full reset, and perhaps a custom ROM to see if it's a hardware or software issue.

Screen Dimming

LG K20 Plus boots up then screen dims about every 5 seconds. Had to find an app to keep the screen on. Went to settings/display and tried various settings but non would work to keep the screen on for any designated time adjustment. Any suggestions? Also, other issue; after setting up the fingerprint security, that doesn't work Phone boots up and on screen says fingerprint not working put in your pin which does work.

Lockscreen anomalies

I'm not sure if i'm posting this in the right place but couldn't find any other more appropriate location. I'm running Oxygen 9.0 build A6013_34_181001 and I've already noticed a few bugs.
I have my phone set to use fingerprint unlock and pattern unlock. Pattern lock is configured such that the pattern line is NOT displayed when I enter it. This works fine, except after a reboot. Upon rebooting the phone I'm prompted for my pattern unlock, and the pattern is displayed when I enter it. After this one instance, the pattern display is correct and consistent with my setting. Subsequent pattern inputs don't display the line, it's just the first one after boot.
I also noticed a strange issue with the fingerprint unlock. When the screen is off and I double tap to turn on the ambient display, normally I put my finger on the fingerprint sensor and the display brightness increases. I'm assuming this is to provide illumination for the fingerprint sensor to function and get a good image of the fingerprint. Sometimes when I put my finger over the sensor the screen doesn't brighten, and the sensor can't read my fingerprint. I know it's detecting my fingerprint and trying to read it since I get the animation on the display around the sensor, the screen just doesn't brighten and the sensor can't read my fingerprint.
There have also been some instances where the double tap on the screen doesn't turn the ambient display on. I can use the power button to wake the phone, and that works fine, but periodically the double tap just won't turn the ambient display on. I like this feature so I can quickly check if there are any pending notifications without having to press any buttons, most often when my phone is lying on my desk.
I haven't been on any of the OnePlus forums yet. Do they have a forum for bug submittals?

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