Bug 108941

Summary: Enabling PP_OVERDRIVE_MASK with dual monitors causes artifacting
Product: DRI Reporter: boukehaarsma23
Component: DRM/AMDgpuAssignee: Default DRI bug account <dri-devel>
Status: NEW --- QA Contact:
Severity: major    
Priority: medium CC: magist3r, yshuiv7
Version: XOrg git   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
i915 platform: i915 features:

Description boukehaarsma23 2018-12-04 13:21:27 UTC
Steps to reproduce:

1) Have dual monitors
2) Enable PP_OVERDRIVE_MASK by flipping the appropriate bit in amdgpu.ppfeaturemask. (For my configuration I used: 0xfffd7fff)
3) See artifacting.

When using default featuremask, or when using a single monitor with the overdrive bit enabled behaves correctly. I heard multiple people who have the same issue, so it does not seem related to my setup.

Linux 4.20-rc5

If additional information is needed please let me know.
Comment 1 Rigo Reddig 2018-12-04 13:44:24 UTC
I've just recently chatted to boukehaarsma23 about it, as it also affects me.

I have uploaded a video of what this looks like which you can see here:


Interestingly the artifact lines appear to be aligned across the screens, vsync? 

The main reason though I first came across this is by trying to manually downclock my GPU. With 2x 60Hz HDMI 1080p monitors attached the GPU is constantly in a higher power state (both mclkc and sclk) and wastes a considerable amount of power at idle. This is not a problem with 1 monitor attached.

Also of note is that even with 2 monitors attached this does not occur on Windows where the GPU idles at 300MCLK/300SCLK and is significantly cooler.

For comparison about power, according to my UPS my system idles at 112-128W when the GPU's are downclocking appropriately(1 monitor). This measurement matches with Windows where the GPU is downclocking to state 0 appropriately.

When it's not downclocking appropriately (2x monitors) it idles at anywhere between 160-176Watt.

2x RX580 Gigabyte 8G (Monitors both on GPU0)
Linux 4.19.4 (Arch Main)
Latest stable KDE Plasma on X

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