Google Pixel 4 90Hz Refresh Is Limited By Display Brightness But Here's A Fix

Google's flagship Pixel 4 lineup has been out a week now, and as anticipated, the new phones debuted with 90Hz displays. The higher refresh rate puts the Pixel 4 and Pixel 4 XL in gaming phone territory, even though these are not classified as gaming handsets. Interestingly, however, it's been discovered the brightness level dictates whether the 90Hz setting actually works.

Outside of playing games that can support framerates above 60 frames per second, a 90Hz refresh rate can make scrolling and navigation on a smartphone even smoother. However, it can also drain a battery faster than a 60Hz setting. To contend with that, Google employs an algorithm to dynamically switch the refresh rate, dropping it from 90Hz to 60Hz in situations where there is not much benefit in going with the faster setting, such as reading a PDF document or ebook.

That is all fine and dandy—Google knows a thing or two about developing algorithms—but Android developer Brian Sefcik did some digging and discovered the Pixel 4 and Pixel 4 XL both reduce the refresh rate to 60Hz if the display brightness is less than 75 percent. It was confirmed by XDA Developer's editor-in-chief Mishaal Rahman.

Sorry, looks like it should be:

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

— Mishaal Rahman (@MishaalRahman) October 23, 2019

Sefcik and Rahman observed the curious restriction by monitoring logs via ADB. We're not sure why Google decided to implement this restriction. Lowering the screen brightness can help regain some of the battery life that might get lost from using a higher refresh rate, so it seems odd these two are not able to work hand-in-hand. Well, not by default, anyway.

Fortunately, this is something that users can manually override. The easiest way to do this is to enable a hidden menu called Developer options by going to Settings > About phone and tapping the build number five times.

Once you have done that, navigate to Settings > System > Developer options > Force 90Hz refresh rate and flip the toggle.

A more complicated workaround requires root access. If you have it, you can configure a different brightness threshold.

"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," Rahman states in a separate Twitter post.

This appears to only affect the Pixel 4 family—the funky brightness restriction does not exist on the ASUS ROG Phone II or OnePlus 7 Pro.