Screen tearing in SteamVR when adaptive sync is enabled on any of the connected monitors.

[joni999]

NVIDIA Open GPU Kernel Modules Version

590.48.01

Please confirm this issue does not happen with the proprietary driver (of the same version). This issue tracker is only for bugs specific to the open kernel driver.

• I confirm that this does not happen with the proprietary driver package.

Operating System and Version

Arch Linux

Kernel Release

6.18.2-2-cachyos

Please confirm you are running a stable release kernel (e.g. not a -rc). We do not accept bug reports for unreleased kernels.

• I am running on a stable kernel release.

Hardware: GPU

GeForce RTX 3090 Ti

Describe the bug

If adaptive sync is enabled on any of my connected monitors and I start SteamVR, the VR headset's displays will experience some kind of screen tearing, making it unusable for VR gaming.

I'm using a Valve Index VR headset.

In the performance graph it will look like this:

Currently the only working configuration is using the proprietary driver and turning off GSP - so it seems to have something to do with GSP.
What it should look like:

A working workaround is setting the following in a modprobe.d file:
options nvidia-modeset conceal_vrr_caps=1

To Reproduce

1. Enable adaptive sync in your monitor's settings and optionally turn it on in your desktop environment's settings (the issue also manifests if you have adaptive sync "off" in your desktop environment's settings)
2. Start SteamVR
3. Put on your VR headset and observe screen tearing and stuttering in the headset's display

Bug Incidence

Always

nvidia-bug-report.log.gz

nvidia-bug-report.log.gz

More Info

There is also a forum thread here:
https://forums.developer.nvidia.com/t/enabling-gsp-makes-steamvr-unplayable-on-rtx-3090ti/298694
If the issue is wrong here, please inform the respective team on your side and close one of the two tickets.

[joni999]

Nvidia user "amrits" on the forum has already opened an internal ticket with number [5014610]:
https://forums.developer.nvidia.com/t/enabling-gsp-makes-steamvr-unplayable-on-rtx-3090ti/298694/8?u=joni_999
But the issue did not go away after they implemented a supposed fix

[Binary-Eater]

I took a look at your forum post. What's really surprising to me is this.

https://forums.developer.nvidia.com/t/enabling-gsp-makes-steamvr-unplayable-on-rtx-3090ti/298694/20

You mention that the proprietary modules with GSP enabled are not producing screen tearing? Are you sure about this? EDIT: missed the bit about conceal_vrr_caps. For whatever content you are running, is vsync enabled in the graphics application?

[Binary-Eater]

Also, would you mind also retesting in the problematic configuration with the NVreg_* kernel parameters CachyOS sets disabled/commented out?

[joni999]

Hi!

SteamVR definietely worked fine with proprietary module & GSP disabled but NOT with GSP enabled, which makes me suspect it's a GSP issue.

I don't think SteamVR runs with VSync enabled but I don't have a way to prove it - do you know how I could check ? There is no setting in SteamVR or the VR games for it at least

Commented the parameters out and tried again, but the tearing still appears.

joni@linuxjoni04 ~> cat /usr/lib/modprobe.d/nvidia.conf  
#
# NVreg_UsePageAttributeTable=1 (Default 0) - Activating the better memory
# management method (PAT). The PAT method creates a partition type table at a
# specific address mapped inside the register and utilizes the memory
# architecture and instruction set more efficiently and faster. If your system
# can support this feature, it should improve CPU performance.
#
# NVreg_InitializeSystemMemoryAllocations=0 (Default 1) - Disables clearing
# system memory allocation before using it for the GPU. Potentially improves
# performance, but at the cost of increased security risks. Write "options
# nvidia NVreg_InitializeSystemMemoryAllocations=1" in
# /etc/modprobe.d/nvidia.conf, if you want to return the default value. Note:
# It is possible to use more memory (?)
#
# NVreg_DynamicPowerManagement=0x02 - Enables the use of dynamic power
# management for Turing generation mobile cards, allowing the dGPU to be
# powered down during idle time.
#
# NVreg_RegistryDwords=RmEnableAggressiveVblank=1
# Reduce time spent in interrupt top half for low latency display interrupts
# by deferring the work until later
#

#options nvidia NVreg_UsePageAttributeTable=1 \
#    NVreg_InitializeSystemMemoryAllocations=0 \
#    NVreg_DynamicPowerManagement=0x02 \
#    NVreg_RegistryDwords=RmEnableAggressiveVblank=1

[Binary-Eater]

I think SteamVR itself has vsync enabled by default and it's a developer setting to try force disabling it or it would have to be force disabled by the usermode graphics driver. I wasn't sure if this was only when a specific game was launched. So the tearing can be seen in the SteamVR app itself?

I think most likely we will need to try having an in-house repro to debug this specific issue.

Commented the parameters out and tried again, but the tearing still appears.

Just sanity checking, this was after a reboot?

[joni999]

Yes I did a reboot after commenting it out :)

There is a "SteamVR lobby" that gets automatically launched when I start SteamVR.
That lobby has the same tearing issue as for example the game Beat Saber.