NVIDIA G-SYNC Compatible (FreeSync) working via AllowGSYNCCompatible

[rafma0]

Batocera build version

43

Your architecture

x86_64

Your Graphic Processor Unit(s) (GPU)

NVIDIA RTX 2070 Super

Issue description

Hi everyone,

I'm opening this issue mostly to document something that worked for me, since I couldn't find any official documentation about it.

I'm using an NVIDIA GPU connected to a Samsung Q80R TV, which has HDMI 2.0b and supports FreeSync.
On Windows, this setup works as expected: I first enable FreeSync Ultimate on the TV, then enable "Enable G-SYNC, G-SYNC Compatible" in the NVIDIA Control Panel, and the TV OSD confirms that FreeSync is active (it shows "FreeSync" and the current FPS).

I wasn't sure if something similar was possible on Batocera, and I couldn't find any documentation about G-SYNC Compatible / FreeSync with NVIDIA.

I added the following file:

/userdata/system/99-nvidia.conf

Section "Screen"
    Identifier "Screen0"
    Option     "metamodes" "nvidia-auto-select {AllowGSYNCCompatible=On}"
EndSection

After rebooting Batocera, the TV OSD already shows FreeSync as active, even before configuring RetroArch.

In RetroArch, I then set:

• Vertical Sync (VSync): OFF
• Sync to Exact Content Framerate (G-Sync, FreeSync): ON

This doesn't increase raw performance, but it reduces latency and, in my case, results in no visible tearing while keeping smooth frame pacing.

I don't know if this is officially supported or just undocumented behavior, but I'm sharing it in case it helps others or can be documented.

Thanks for the great work on Batocera.

Detailed reproduction steps

See issue description above. Steps already described there.

Details of any attempts to fix this yourself

No response

Details of any modifications you have made to Batocera.

Only the Xorg configuration file mentioned in the issue description.

Logs and data

Behavior confirmed via TV OSD.