The Google Pixel 4 and the Pixel 4 XL were announced last week and the duo was savagely leaked, with Google contributing to those leaks through official revelations. We weren’t expecting bells and whistles since most of the features were already out in the open – many of which Google didn’t even talk about at the Pixel 4 keynote – but, the new, smoother 90Hz display on the new Pixel smartphones was among the key features that a lot of us were anticipating. While references in the phone’s source code gave away to the 90Hz display at least a month ahead of the official launch, there’s something interesting he recently discovered.

Pixel 4 XDA Forums / Pixel 4 XL XDA Forums

Just like the OnePlus 7 Pro and the new OnePlus 7T series, the 90Hz refresh rate is not valid for all scenarios and only works in certain use cases or supported apps. Apparently, Google is using an algorithm to reduce the refresh rate of the Pixel 4/4 XL’s display to 60Hz smartly in cases such as when you’re watching a video or reading a PDF or ebook and it automatically kicks back in when you scroll.

However, a peculiar behavior in this regard was discovered Android developer, Brian Sefcik, and confirmed by our Editor-in-Chief, Mishaal Rahman. They determined the Pixel 4’s display automatically switching between 90Hz and 60Hz refresh rate based on the brightness of the display.

Sorry, looks like it should be:

If brightness <= 75%, display id = 2.
If brightness > 75%, display id = 1.

— Mishaal Rahman (@MishaalRahman) October 23, 2019

Using the Logcat tool via ADB, Mishaal figured that the Pixel 4’s display automatically turns down to 60Hz when the brightness is below 75%. It’s unclear why Google has tied the setting to brightness and Mishaal is currently probing Smooth Display APK to see if there are other parameters that may cause the display to switch to 60Hz automatically.

In framework-res__auto_generated_rro_vendor (a framework overlay in /vendor/overlay), the value “config_brightnessThresholdsOfPeakRefreshRate” in arrays.xml is set to 74. With root, we can easily change this threshold.

— Mishaal Rahman (@MishaalRahman) October 23, 2019

Notably, neither OnePlus 7 Pro nor the ASUS ROG Phone II displays this behavior. This behavior is most likely to be intentional and not a bug but we’re not sure if this is an attempt by Google to avoid complaints regarding the smooth display draining the small batteries on the Pixel 4/4 XL too quickly.

Force 90Hz Refresh Rate on Pixel 4

Meanwhile, if you have a Pixel 4/4 XL and want to always enjoy the 90Hz display, you can set the display to stay at 90Hz permanently by forcing the option from Developer Settings. This will continue to work irrespective of the brightness you’re using your phone at.

Dev option to force 90Hz at all times pic.twitter.com/0LuxaZgUjK

— Mishaal Rahman (@MishaalRahman) October 15, 2019

We’ll update the article with more information, so stay tuned!