# Hybrid GPU Configuration

Guide for configuring AMD + NVIDIA hybrid graphics on Legion laptops with Hyprland.

## Hardware Topology

On Legion laptops with hybrid graphics:
- **AMD iGPU (card1)**: Drives the laptop display (eDP-2)
- **NVIDIA dGPU (card0)**: Drives external displays (DP-1, DP-2 via USB-C)

This is hardware-wired and cannot be changed via software.

## BIOS Configuration

**Critical:** Set GPU mode to **Hybrid/Dynamic** (not Discrete).

Discrete mode may cause:
- Lower resolution options on laptop display
- Display detection issues
- Power management problems

## NVIDIA Driver Setup

### Install Drivers
```bash
emerge x11-drivers/nvidia-drivers
```

### Blacklist Nouveau
```bash
echo "blacklist nouveau" > /etc/modprobe.d/blacklist-nouveau.conf
echo "options nouveau modeset=0" >> /etc/modprobe.d/blacklist-nouveau.conf
```

### Enable DRM
```bash
echo "options nvidia_drm modeset=1 fbdev=1" > /etc/modprobe.d/nvidia.conf
```

### GRUB Configuration
Add to `/etc/default/grub`:
```bash
GRUB_CMDLINE_LINUX_DEFAULT="nvidia_drm.modeset=1 acpi_backlight=native"
```

Regenerate:
```bash
grub-mkconfig -o /boot/grub/grub.cfg
```

### Dracut Configuration
Create `/etc/dracut.conf.d/nvidia.conf`:
```bash
add_drivers+=" nvidia nvidia_modeset nvidia_uvm nvidia_drm "
force_drivers+=" nvidia nvidia_modeset nvidia_uvm nvidia_drm "
```

Rebuild initramfs:
```bash
emerge --config sys-kernel/gentoo-kernel
```

## Hyprland Configuration

### GPU Auto-Detection

Hyprland should auto-detect GPUs. **Do NOT** set these variables in your config:
```bash
# Leave these commented out for auto-detection
# env = AQ_DRM_DEVICES,/dev/dri/card0:/dev/dri/card1
# env = AQ_MGPU_NO_EXPLICIT,1
```

If auto-detection fails, try explicit order as fallback:
```bash
env = AQ_DRM_DEVICES,/dev/dri/card1:/dev/dri/card0
env = AQ_MGPU_NO_EXPLICIT,1
```

### Monitor Configuration

Example triple-monitor layout:
```bash
# Left external | Center laptop | Right external
monitor=DP-1, 1920x1080@60, 0x0, 1
monitor=eDP-2, 1920x1080@60, 1920x0, 1
monitor=DP-2, 1920x1080@60, 3840x0, 1
```

Use `hyprctl monitors` to get your monitor names.

### Cursor Fix (Multi-GPU)

Disable hardware cursors to prevent duplicate/missing cursor issues:

In `~/.config/hypr/configs/SystemSettings.conf`:
```
cursor {
    no_hardware_cursors = 2
    default_monitor = eDP-2
}
```

### Workspace Assignment

Assign workspaces to specific monitors:
```bash
workspace = 1, monitor:eDP-2, default:true
workspace = 2, monitor:DP-1, default:true
workspace = 3, monitor:DP-2, default:true
```

## Gaming

Games automatically use the NVIDIA GPU in hybrid mode. No `prime-run` needed for most cases.

If a game isn't using the NVIDIA GPU:
```bash
prime-run <application>
```

Or set environment variables:
```bash
__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia <application>
```

## Backlight Control

The laptop backlight is controlled by the AMD iGPU. If brightness controls don't work:

1. Check available backlight devices:
   ```bash
   ls /sys/class/backlight/
   ```

2. Use the correct device in brightness scripts (usually `amdgpu_bl1` for Legion).

3. GRUB setting helps:
   ```bash
   GRUB_CMDLINE_LINUX_DEFAULT="... acpi_backlight=native"
   ```

## Troubleshooting

### Pink/Artifacts on External Monitors

1. Ensure BIOS is set to Hybrid/Dynamic mode
2. Try letting Hyprland auto-detect GPUs (comment out AQ_* variables)
3. If auto-detect fails, try explicit GPU order

### External Monitors Not Detected

1. Check connections (USB-C to DisplayPort)
2. Verify NVIDIA driver is loaded: `lsmod | grep nvidia`
3. Check Xorg/Wayland logs for errors

### Performance Issues

1. Verify NVIDIA persistence daemon is running
2. Check power profile: `powerprofilesctl get`
3. Monitor GPU usage: `nvidia-smi`

### Screen Tearing

Ensure NVIDIA DRM is enabled:
```bash
cat /sys/module/nvidia_drm/parameters/modeset
# Should return: Y
```