How To Guide Screen refresh rate twinkering

foobar66 · Nov 26, 2021

Screen refresh rate is controlled by several variables, 3 which I found are:

Code:

# getprop ro.surface_flinger.use_content_detection_for_refresh_rate

This instructs the screen compositor (surface flinger) to look at screen content to control screen refresh rate. 'true' by default; you will need root and Magisk's resetprop to override it, e.g.

Code:

# resetprop ro.surface_flinger.use_content_detection_for_refresh_rate false

But note that that does not stick after reboot, you will need a magisk module to force that upon boot. Add the property to system.prop file in the magisk module top directory.

Then:

Code:

# settings get system min_refresh_rate

0 by default; you can set e.g. to '60'

Code:

# settings put system min_refresh_rate 60

And the peak refresh:

Code:

# settings get system peak_refresh_rate

60 or 120 depending on toggle 'Smooth display' in Settings.

When you use 'Force peak refresh rate' in developer options then:

Code:

# settings list system | grep refresh
min_refresh_rate=120.00001

Weird number by the way. Anyway that forces the driver into 120Hz continuously.

I have personally set min=60, peak=120 and the surface flinger content detection to 'false' ... just to see how this goes for a couple of days.

And finally some other properties related to surface_flinger:

Code:

# indicates whether SurfaceFlinger should use refresh rate switching on the device, e.g. between 60 and 120 Hz (default: true)
ro.surface_flinger.refresh_rate_switching

# value used by the Scheduler to trigger display power inactivity callbacks (default: 1000)
ro.surface_flinger.set_display_power_timer_ms

# used by the Scheduler to trigger touch inactivity callbacks that will switch display to a lower refresh rate (default: 200)
ro.surface_flinger.set_touch_timer_ms

tids2k · Nov 26, 2021

Interesting ...

antoniovj1 · Nov 26, 2021

It's possible to set minimum to 10Hz?

PuffDaddy_d · Dec 6, 2021

foobar66 said:
I have personally set min=60, peak=120 and the surface flinger content detection to 'false' ... just to see how this goes for a couple of days.

How did it go?

foobar66 · Dec 6, 2021

PuffDaddy_d said:
How did it go?

So far no issues ... all working fine. I have now set the minimum as well to 120 Hz ... just to see how that might affect things ...

foobar66 · Dec 11, 2021

foobar66 said:
So far no issues ... all working fine. I have now set the minimum as well to 120 Hz ... just to see how that might affect things ...

LOL ... as expected ... significantly more battery drain keeping the screen to 120 Hz all the time.
But scrolling ... oh so smooth ...

Looking for a middle with increased ground with ro.surface_flinger.set_touch_timer_ms to avoid switching too soon to lower rate (and ro.surface_flinger.use_content_detection_for_refresh_rate=false to avoid switching to lower rate based on content).

kevinireland11 · Dec 11, 2021

foobar66 said:
LOL ... as expected ... significantly more battery drain keeping the screen to 120 Hz all the time.
But scrolling ... oh so smooth ...

Looking for a middle with increased ground with ro.surface_flinger.set_touch_timer_ms to avoid switching too soon to lower rate (and ro.surface_flinger.use_content_detection_for_refresh_rate=false to avoid switching to lower rate based on content).

Can min=90? Or will it only run between 60-120?

foobar66 · Dec 11, 2021

kevinireland11 said:
Can min=90? Or will it only run between 60-120?

Not sure ... I guess it can ... I have not yet found if there is a kernel flag which can be checked to obtain the current (actual) frequency of the display.

foobar66 · Dec 11, 2021

Actually, you can see the refresh rate of the screen.
Go to developer settings. There is a toggle there called 'Show refresh rate' ;-)
Tried setting min rate to 90 ... but does not work via this mechanism.

Code:

settings put system min_refresh_rate 90

It switches the minimum rate to 120.
So looks like only 60 and 120 are accepted.

If you set system peak_refresh_rate to 60, then the screen will always be in 60 Hz. That is very clearly visible when scrolling.

When you touch the screen, it seems to immediately switch into 120 HZ as there is of course a possibility that you will start scrolling ... so makes sense. As soon as you lift your finger and the screen content is not moving the frequency is lowered to 60.

Laptapper · Oct 18, 2022

foobar66 said:
Screen refresh rate is controlled by several variables, 3 which I found are:

Code:

# getprop ro.surface_flinger.use_content_detection_for_refresh_rate

This instructs the screen compositor (surface flinger) to look at screen content to control screen refresh rate. 'true' by default; you will need root and Magisk's resetprop to override it, e.g.

Code:

# resetprop ro.surface_flinger.use_content_detection_for_refresh_rate false

But note that that does not stick after reboot, you will need a magisk module to force that upon boot. Add the property to system.prop file in the magisk module top directory.

Then:

Code:

# settings get system min_refresh_rate

0 by default; you can set e.g. to '60'

Code:

# settings put system min_refresh_rate 60

And the peak refresh:

Code:

# settings get system peak_refresh_rate

60 or 120 depending on toggle 'Smooth display' in Settings.

When you use 'Force peak refresh rate' in developer options then:

Code:

# settings list system | grep refresh min_refresh_rate=120.00001

Weird number by the way. Anyway that forces the driver into 120Hz continuously.

I have personally set min=60, peak=120 and the surface flinger content detection to 'false' ... just to see how this goes for a couple of days.

And finally some other properties related to surface_flinger:

Code:

# indicates whether SurfaceFlinger should use refresh rate switching on the device, e.g. between 60 and 120 Hz (default: true) ro.surface_flinger.refresh_rate_switching # value used by the Scheduler to trigger display power inactivity callbacks (default: 1000) ro.surface_flinger.set_display_power_timer_ms # used by the Scheduler to trigger touch inactivity callbacks that will switch display to a lower refresh rate (default: 200) ro.surface_flinger.set_touch_timer_ms

Hi, what's your experience with these changings now?
Can you send the exact settings for a script please?

73sydney · Nov 22, 2022

For Samsung devices with high refresh rate displays there is Galaxy Max Hz, that has an adaptive mode (Pixel default from what i understand in the few hours ive been back on Pixel (6 Pro)) and also a screen off low rate, and also per app granular control. So far havent seen an equivalent for Pixel, but hopefully a matter of time

_Vortex95 · Jan 7, 2023

How to get magisk resteprop? I can't find anything about it

73sydney · Jan 7, 2023

_Vortex95 said:
How to get magisk resteprop? I can't find anything about it

Its an applet of magisk, its functions are outlined here:

Magisk/tools.md at master · topjohnwu/Magisk

The Magic Mask for Android. Contribute to topjohnwu/Magisk development by creating an account on GitHub.

github.com

short version, you could call it via script (post-fs-data.sh OR service.sh - depending on at which point of the boot process you wanted to use it)

boot stages of magisk explained here:

Magisk/details.md at master · topjohnwu/Magisk

The Magic Mask for Android. Contribute to topjohnwu/Magisk development by creating an account on GitHub.

github.com

service.sh is preferred (see here for why: https://topjohnwu.github.io/Magisk/guides.html#boot-scripts )

but

as mentioned it would be easier to add it to a system.prop file it the root folder of a magisk module and try that first

and if you were looking to create a magisk module and fiddle, this template by @Zackptg5 is what id recommend and i use:

GitHub - Zackptg5/MMT-Extended: Magisk Module Template Extended

Magisk Module Template Extended. Contribute to Zackptg5/MMT-Extended development by creating an account on GitHub.

github.com

and his excellent wiki:

Home

Magisk Module Template Extended. Contribute to Zackptg5/MMT-Extended development by creating an account on GitHub.

github.com

A module might be as simple as (i could do it in about 5 minutes, (and it shouldnt take you much more as a 1st timer, as this is a simple module), but people should learn this themselves):

1) Download the MMT- Extended template linked above buy going to the github link, then click (towards top) green Code button, then Download Zip or click here: https://github.com/Zackptg5/MMT-Extended/archive/refs/heads/master.zip

2) Extract the zip somewhere, giving you a folder "MMT-Extended-master"

3) Rename "MMT-Extended-master" to the name of the module youre creating

4) Descend into this folder, delete what you dont need - in this case:

system folder
zygisk folder
changelog.md (unless you plane to update and maintain a changelog)
update.json (unless you plan to submit to a repo)

5) Edit module.prop to set values for the module name etc (remove the update updateJson line if you removed the update.json file)

6) Add a system.prop file in the folder

7) Open with a good text editor (notepad++ is reocmmended) and add the necessary line:

Code:

ro.surface_flinger.use_content_detection_for_refresh_rate false

8) Save the file

9) Select all the contents of the folder, and compress (preferably with anything but WinRAR (as it can create wonlky zip files))

10) Transfer to device, flash via Magisk Manager (NOT TWRP) and test

Only if this way fails would i bother with trying to add the resetprop method buy adding the

Code:

resetprop ro.surface_flinger.use_content_detection_for_refresh_rate false

line in service.sh (created in the folder), usually people would try this way with a delay (sleep <seconds>) to try and change it much later than the resetprop stage in system.prop...timing can sometimes be everything

Magisk modules dont need to be hard and thats a VERY simple one

73sydney · Jan 7, 2023

Came across this in my travels today(not tested by me), just linking for interested parties

GitHub - yc9559/dfps: Dynamic screen refresh rate controller for Android 10+

Dynamic screen refresh rate controller for Android 10+ - GitHub - yc9559/dfps: Dynamic screen refresh rate controller for Android 10+

github.com

heni63 · Sunday at 3:46 AM

I have a Pixel 6a, might it be possible to reduce the Refresh Rate to 30Hz with this method?

Btw: Thank you for sharing your knowledge/findings guys!

How To Guide Screen refresh rate twinkering

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