For the last few months I have been delving myself in android root and custom ROM scene, from learning the basics to tinkering with kernels settings to find a solution or a combination of software/ROM/driver/kernel that would allow me to use a new smartphone without eye strain.
I get eye strain from PWM flickering, and I also get eye strain from graphics driver. So to find a usable smartphone, I need to eliminate these 2 source of eye strain.
I have always been able to use HTC phones with SuperLCD3 display without any eye strain whatsoever (on Lollipop). So my first try is the HTC U Ultra.
HTC U Ultra
This phone is using SuperLCD5 display panel, and has no PWM, as confirmed by notebookcheck.net. So this is good. But unfortunately, despite having no PWM, this phone gave me the absolute worse eye strain I ever had compared to all other smartphones I have tried before, and I have tried quite a lot of phones Samsung Note 5, LG V10, Mate 7 etc. When using the HTC U Ultra, my eyes feels like it is burning, and I get the eye strain very fast too, and it lingers much longer after I stopped looking at the phone. This phone is running Android 7.0.
Here's what I have tried:
- rooted the phone using superSU and Magisk, installed TWRP
- installed cf.lumen, tried all 3 root drivers (compatibility, anti-flicker, and performance), all give me eye strain.
- installed custom ROM LeeDroid, which has its own graphics tweaks and control, hoping that this might override whatever it is in android graphics driver that is cauing the eye strain. Still no dice, the eye strain is still there. But I do noticed that using the custom ROM's advance features, if I disable the Ambient Display, I get less eye strain. If I enable Ambient Display, I get eye strain much faster.
- tried kernel auditor, played around with kernel settings, CPU guvernors, GPU guvernors
Result - still get severe eye strain. One time I forced myself to watch youtube on this phone for 45 minutes, hoping that my eyes will get use to the display. I get eye strain that lasted for 2 days, it was horrible. I never get eye strain that lingers for so long, even after waking up in the morning I can still feel the eye strain. I am trying to install another kernel driver, which is the KCAL driver. This is still in progress. This is my last ditch effort for this phone. If this doesnt work, then I will sell this phone.
Samsung S7 Edge
I bought this phone even though it has PWM, I decided to give it a try because there is a custom flicker-free kernel that will eliminate the PWM, and this phone has a lot of custom ROMs available. The phone comes with android Marshmallow.
Here is what I have tried:
- rooted the phone, installed TWRP
- installed custom flicker-free kernel by wootever on stock ROM. The kernel works, no more PWM, but I still get eye strain (when using with stock android marshmallow). Had a lot of problem trying to get this custom kernel to work on marshmallow, but eventually it works.
- upgraded to Nougat. Installed the flicker-free kernel. Still get eye strain.
- reinstalled the stock marshmallow ROM, installed custom TGPROM, Batman ROM, eye strain.
- installed custom TGP kernel (with PWM-free feature) on top of custom ROM, tried mTweaks, Spectrum, CPU governers, GPU governors - still eye strain.
- reinstalled Nougat stock rom, installed Superman ROM, eye strain. Installed TGP custom kernel on top of custom ROM. Eye strain.
- installed older and newer of custom TGP kernel (flicker free with Mali graphics driver) on Marshmallow - eye strain.
- installed older and newer versions of custom TGP kernel (flicker free with stock graphics driver and Mali driver) on Nougat - still eye strain.
Its very frustrating. I was hoping that certain combinations of OS, custom flicker-free kernel, and/or custom ROM might be able to give an eye strain free experience. But the eye strain is still there. With all these custom kernel and ROMs, I can use the phone, but cant look at the phone for more than 5 minutes. Which is the same if I didnt do anything to the phone at all. This is okay for quick glance at the phone for quick calls or messaging. But I wanted a phone that I use fully, like watching youtube, composing long emails, and just do productivity stuff on the phone.
The eye strain from Samsung S7 Edge after installing the flicker free kernel is noticeably different than the HTC U Ultra eye strain.
- Samsung S7 Edge stock - has PWM - the strain is mainly inside my eye balls
- Samsung S7 Edge - flicker free kernel (no PWM) and various combinations of custom ROMs - eye strain is not just in eye balls, but I feel the strain in my entire head. But once I stopped looking at the phone, the strain doesnt linger very long.
- HTC U Ultra - mainly inside my eyes and a bit, feels like there is a vertical piece of paper (or layer of something) inside my eye balls, and the strain is like fire burning this paper or this layer of something. And the strain lingers for a long time.
Looks like the search still continues. Sigh.