hardware/16IMH9: add README.md

modules/hardware/lenovo/yoga/16IMH9/README.md

@@ -0,0 +1,27 @@
+# Lenovo Yoga Pro 9i 16IMH9
+
+Optimized hardware configuration for Lenovo Yoga Pro 9i (16IMH9).
+
+______________________________________________________________________
+
+## Audio
+
+- **Workaround**: Bass speakers malfunction due to runtime power management bugs for TAS2781 amp (kernel 6.12.x+).
+  - Blacklists `snd_hda_scodec_tas2781_i2c` kernel module.
+  - Runs [`turn-on-speakers.sh`](turn-on-speakers.sh) to power on TAS2781 amp and bass speakers via I2C.
+  - Unmutes headphones with `amixer`.
+- Further enhances sound quality with EasyEffects preset: [`16IMH9.json`](./16IMH9.json).
+
+______________________________________________________________________
+
+## Graphics
+
+- Hybrid NVIDIA PRIME setup with Render Offload:
+  - Intel GPU: `intelBusId = "PCI:0:2:0"`.
+  - NVIDIA GPU: `nvidiaBusId = "PCI:1:0:0"`.
+- Includes specialisation `nvidia-sync` to enable PRIME Synchronization.
+- **Workaround**: High power usage while watching videos.
+  - Disables `hardware.nvidia.videoAcceleration` to allow NVIDIA GPU to sleep during video playback.
+  - Uses integrated Intel Arc GPU for WebRender.
+
+______________________________________________________________________

modules/hardware/lenovo/yoga/16IMH9/default.nix

@@ -81,6 +81,7 @@ in {
 
   systemd = {
     services.turn-on-speakers = {
+      # Due to bugs in the snd_hda_scodec_tas2781_i2c module, the best way to have functional speakers is to run a small script to turn the bass speakers on via i2c.
       enable = true;
 
       after = [