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Change Intel i915's PWM Frequency on Boot

The problem with PWM frequency is described in ArchLinux Wiki1.

To set desired PWM frequency on boot, create a systemd service file:

/etc/systemd/system/pwmfrequency@.service

with the following content:

[Unit]
Description=LED PWM frequency
After=graphical.target

[Service]
ExecStart=/usr/bin/intel_reg write 0xC8254 %I
Type=oneshot
RemainAfterExit=yes

[Install]
WantedBy=default.target

Finally, create a systemd service:

systemctl enable pwmfrequency@0x7a107a1

The hex number after the '@' symbol is the desired PWM frequency value. You can calculate it here: Eliminate backlight flicker with Intel i915 | 127.0.0.12.

  1. Backlight - ArchWiki, [no date]. Online. [Accessed 9 June 2023]. Available from: https://wiki.archlinux.org/title/backlight#Backlight_PWM_modulation_frequency_.28Intel_i915_only.29 ↩

  2. Eliminate backlight flicker with Intel i915 | 127.0.0.1, [no date]. Online. [Accessed 9 June 2023]. Available from: https://127001.me/post/eliminate-backlight-flicker-with-i915/ ↩

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