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README.md

@@ -34,6 +34,47 @@ Section "Device"
     Option "TearFree"    "true"
 EndSection
 ```
+    - amd: xf86-video-amdgpu (`VariableRefresh` = FreeSync, fullscreen apps only under Xorg)
+    - sudo -e /etc/X11/xorg.conf.d/20-amdgpu.conf
+```
+Section "Device"
+    Identifier "AMD"
+    Driver "amdgpu"
+    Option "VariableRefresh" "true"
+    Option "TearFree" "true"
+EndSection
+```
+## High refresh rate flicker (AMD):
+- At high refresh rates (240Hz+) the vblank can be too short for the GPU to
+  switch VRAM clock unnoticed, so the desktop flickers under changing load.
+  Windows avoids it by keeping VRAM clock high; amdgpu on Linux may not.
+- Check: if the `*` jumps between levels while idle, this is likely the cause.
+```bash
+watch -n0.2 cat /sys/class/drm/card*/device/pp_dpm_mclk
+```
+- Fix 1: run the desktop at a lower rate (`i3/config` uses 120Hz). Find the
+  output name with `xrandr` (e.g. `DisplayPort-0`) and adjust it there:
+```bash
+xrandr --output DisplayPort-0 --mode 1920x1080 --rate 120
+```
+- sway: same idea in `sway/config` (`swaymsg -t get_outputs` for the name).
+  Keep `adaptive_sync off` there — sway applies it to the whole desktop, which
+  can stutter/flicker:
+```
+output DP-1 mode 1920x1080@120Hz adaptive_sync off
+```
+- Fix 2: keep the high rate and pin VRAM clock to its top level (more idle
+  power, resets on reboot; top level is the last line of `pp_dpm_mclk`):
+```bash
+echo manual | sudo tee /sys/class/drm/card*/device/power_dpm_force_performance_level
+echo 3 | sudo tee /sys/class/drm/card*/device/pp_dpm_mclk
+```
+- Gaming: 120Hz + FreeSync is plenty for ~60fps games (VRR covers the dips).
+  Cap fps a few below max refresh so VRR stays active, e.g. Dota 2 console
+  `fps_max 117`. Under Xorg, VRR applies to fullscreen games only; under sway
+  with `adaptive_sync off` games run without it.
+- To turn off FreeSync for a single game (Xorg): `adaptive_sync=false %command%`
+  (Steam launch options).
 ![stones](./screenshots/Screenshot_20240503_095414.png)
 
 ## Installing dependencies
@@ -49,8 +90,8 @@ or manual/cargo install.
 ```bash
 sudo pacman -S i3-wm i3status i3blocks sway swaybg swaylock swayidle \
   waybar polybar rofi alacritty dex snixembed \
-  xss-lock xorg-xset xclip scrot imagemagick i3lock \
-  network-manager-applet blueman gnome-keyring \
+  xss-lock xorg-xset xorg-xrandr xclip scrot imagemagick i3lock \
+  network-manager-applet blueman gnome-keyring polkit-gnome \
   pipewire wireplumber pipewire-pulse pipewire-alsa pipewire-jack \
   pasystray playerctl brightnessctl \
   fcitx5 fcitx5-im fcitx5-configtool
@@ -63,10 +104,10 @@ sudo emerge --ask \
   gui-wm/sway gui-apps/swaybg gui-apps/swaylock gui-apps/swayidle \
   gui-apps/waybar x11-misc/polybar x11-misc/rofi x11-terms/alacritty \
   x11-misc/dex x11-misc/snixembed \
-  x11-misc/xss-lock x11-apps/xset x11-misc/xclip media-gfx/scrot \
+  x11-misc/xss-lock x11-apps/xset x11-apps/xrandr x11-misc/xclip media-gfx/scrot \
   media-gfx/imagemagick x11-misc/i3lock \
   net-misc/networkmanager net-misc/network-manager-applet net-wireless/blueman \
-  app-crypt/gnome-keyring \
+  app-crypt/gnome-keyring gnome-extra/polkit-gnome \
   media-video/pipewire media-video/wireplumber media-sound/playerctl \
   app-i18n/fcitx app-i18n/fcitx-qt app-i18n/fcitx-gtk
 ```