RadeonSI Disables SDMA For Polaris To Fix Corruption Bugs

[phoronix]

Phoronix: RadeonSI Disables SDMA For Polaris To Fix Corruption Bugs

For those plagued by OpenGL corruption issues with the RadeonSI driver on Polaris GPUs like the Radeon RX 580, System DMA (SDMA) support is now being disabled as a workaround...

http://www.phoronix.com/scan.php?page=news_item&px=RadeonSI-Disables-Polaris-SDMA

[RBilettess]

Sorry for the question, but is my understanding correct that Mesa disables SDMA, because the AMDGPU driver has issues or has this to be seen differently?

[geearf]

What performance loss could we expect from the 2 sdma disabling?

[Xicronic]

Disabling and never fixing seems like a trend for AMD. Intel GPUs can't come soon enough...

[agd5f]

Sorry for the question, but is my understanding correct that Mesa disables SDMA, because the AMDGPU driver has issues or has this to be seen differently?

Not necessarily kernel issue at least with pre-navi parts. More likely some interactions between GFX and SDMA in mesa. On pre-navi parts SDMA and GFX are not cache coherent so there may be some missing synchronizations between the two.

[Space Heater]

I wonder what could be done to improve the "debuggability" of these low level driver problems, because DMA seems to be a perennial issue.

[wizard69]

Disabling and never fixing seems like a trend for AMD. Intel GPUs can't come soon enough...

Let’s not jump to conclusions here. Sometimes the right thing to do is to disable things that don’t work right or have no future.

No that doesn’t excuse the of software engineering support at AMD but I’m really hoping that their current success results in a much larger software staff. Sales leads to hiring people and the one place that needs staff is in software development.

[Mario Junior]

Now I understand why so many artifacts are appearing when playing TF2 using an RX570 on Gentoo.

[r1348]

I did notice some corruption/artifacts when playing Deus Ex: Mankind Divided on my RX580, no issues at all on all Vulkan games though.

[xorbe]

So this works on Windows but not Linux?