The screen becomes darker whenever the fps drops to 60

[argaman48]

The colors on the screen very visibly become darker about a second after going in or out of anything when using the automatic refresh rate option, it could be when I'm going between apps, opening a new page or even when pulling down the notification panel, it happens all the time.
Video example: https://imgur.com/a/zVJPYyL
Now I think I found the source of the issue.
Enabling the "low brightness DC dimming" option in the display setting, which is only allowed when the phone is on 60fps, solves the issue completely by simply always being darker, but then again, you must force it to be on 60 fps.
So I tried going back to the automatic refresh rate, but now I monitored the fps, and the issue became very clear.
Whenever the fps drops to 60 the DC dimming is probably enabled automatically, even when disabled manually on the settings, causing the screen to become darker whenever it switches between 60 and other refresh rates, since this feature is not supported on higher ones.
Video example: https://imgur.com/a/JK9tAtR
Look at the color of the keyboard and notification panel when the fps switches from 90 to 60 and vice versa, note that it is more visible than it looks on the video

[argaman48]

Mattias_ASUS

Hi!

I have now created a ticket to R&D so they can take a look at it 🙂

View post

Thanks a lot! Great to see you devs actually care!
Already giving me more reasons to recommend this phone to others 🙂

[Mattias_ASUS]

Hello everyone!
I just got a reply from R&D, this is what I got.
Because the screen flashes rate supported by each APP and interface is different, this is a normal reaction that the naked eye may see when switching, If the screen is set on locked 60hz this can fix the issue.

When the refresh rate is set to AUTO, if the refresh rate changes from 90hz to 60hz, which does not support DC dimming,
It must be set to a fixed refresh rate of 60hz since that's the only setting that supports DC dimming.
This seems to be part of hardware limitations and nothing that can be adjusted by firmware.

[Danishblunt]

Mattias_ASUS

Hello everyone!

I just got a reply from R&D, this is what I got.

• Because the screen flashes rate supported by each APP and interface is different, this is a normal reaction that the naked eye may see when switching, If the screen is set on locked 60hz this can fix the issue.
• 
  
• When the refresh rate is set to AUTO, if the refresh rate changes from 90hz to 60hz, which does not support DC dimming,
• It must be set to a fixed refresh rate of 60hz since that's the only setting that supports DC dimming.

This seems to be part of hardware limitations and nothing that can be adjusted by firmware.

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You can absolutely fix this by firmware. I am literal proof that it's software based and fixable.

Danishblunt

So as of today the 21.03.2021 color banding has been defeated. Now at the beginning I was under the impression that the crappy color banding was caused by pixelworks and guess what?

It wasn't.

Infact the reason this happened was actually because of ASUS not wanting to implement any type of gamma correction at all, while other manufacturers like nubia and oneplus have infact added gamma correction in their kernels. So today I simply stole some code from Oneplus 8 kernel like the naughty naughty boy I am and magic has happened. So what are the results of this?

https://i.imgur.com/wL3zpMR.jpg

https://i.imgur.com/Pbx8qvI.jpg

https://i.imgur.com/dg2BBO0.jpg

Now as you can see the difference is absolutely insane. Blacks have returned, no pixelation and the screen looks absolutely georgous! Honestly this screen after calibration seems absolutely amazing, ASUS was not lying when they said that these panels are actually high quality. Granted the quality of the screen cannot be seen in those pictures very well as smartphone cameras have great difficulty catching stuff in the dark with huge amount of details. I took a closer shot as well to show that even the black crush is quite in check as well:

https://i.imgur.com/fVy9I8g.jpg

How exacly an absolutely new guy like me who has extremely little experience with kernel development could fix an issue i looked at in weeks while the experienced asus team didn't get the solution until this date is beyond me right now. I hope that the devs will fix it very soon now that they know they can simply nab code from nubia or oneplus and some modifications, today my SSD died with my ubuntu and kernel sourcecode on it, so only thing I have left is a flashable zip file that would most likely crash on 75% of rog3 devices due to extreme amount of undervolt, i will still share to those who want to try, but successrate won't be high :'D

At this point I want to thank Freak07 for introducing and helping me to get into kernel development much faster than I would have taken by myself.

Colorbanding defeated

its true that DC Dimming changes the screens color reproduction, but this can be fixed by recalibrating the screen with a proper profiles.

[clavo]

Hi @Mattias_ASUS,
I'm sorry to say this, but it sounds like ignorance on the part of the devs. As I have already described, you can see the color changes not only when switching between 90Hz and 60Hz, but also when switching between 120Hz and 90Hz. Since the latter doesn't support DC dimming, that's definitely not (the only) cause.
I'm totally with @Danishblunt here, it's probably due to incorrect/bad calibration at 90Hz.

[Danishblunt]

clavo

Hi @Mattias_ASUS,

I'm sorry to say this, but it sounds like ignorance on the part of the devs. As I have already described, you can see the color changes not only when switching between 90Hz and 60Hz, but also when switching between 120Hz and 90Hz. Since the latter doesn't support DC dimming, that's definitely not (the only) cause.

I'm totally with @Danishblunt here, it's probably due to incorrect/bad calibration at 90Hz.

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The problem here is that the devs might even not be able to touch the calibration due to licensing issues. When you brand something as "calibrated by pixelworks" u cant just recalibrate yourself with an update without having 100% consent and approval from pixelworks, otherwise you break contract with pixelworks and have to pay big stacks.
Also keep in mind, mattias is a nice guy who tries his best, hes active and does whatever he can. He is NOT a developer but asks the team responsible to communicate between the devs and the community mods. Its not his fault that he gets that answer. Its unreasonable to believe the devs respond here.
From experience of being a rog3 user and seeing same complaints on zf8 id say its safe to say either they wont do anything cuz they arent allowed to or wont because they dont care, regardless of the reason, dont expect a fix. At this point a fix to the zf9 would trigger the rog 3 and zf8 users.