Some Of The AMDGPU Changes Being Worked On For Linux 4.8

[bridgman]

Can the amgpu kernel driver alone (w/o the amdgpu-pro component) be used in lieu of radeonsi?

They are very different things - radeonsi is a userspace driver that implements HW support for Mesa (OpenGL, video encode/decode, OpenCL via clover) while the amdgpu kernel driver is a typical kernel driver, providing robust low-level access to hardware.

Radeonsi communicates with HW through either radeon or amdgpu kernel drivers, depending on what is in use on each GPU.

[Chewi]

Has anyone here successfully managed to run the drm-next-4.8-wip kernel? I got my RX 480 yesterday and was quite disappointed to find the mainline kernel doesn't give you HDMI audio. I'd be happy to run the DAL kernel as I normally build my kernel from git anyway but when I tried that branch, I got a kernel panic when starting X. Also, despite the name, it seems to be Linux 4.6?

[bridgman]

The drm-next-4.8-wip branch is not what you want for RX 480 - the Polaris changes are going into 4.7 not 4.8.

Right now you should use either polaris-test (if you want to duplicate what Michael used) or drm-fixes-4.7 (which includes everything in polaris-test plus a few additional fixes).

The drm-next-4.8-wip branch seems to be 4.7-based to me - on the 5th page IIRC you can see 4.7-rc2.

[Chewi]

The drm-next-4.8-wip branch is not what you want for RX 480 - the Polaris changes are going into 4.7 not 4.8.

Ah sorry, bit tired this morning and thought this thread was about DAL. I actually meant the drm-next-4.8-wip-dal branch and that's what I tried. As the Makefile shows, it is 4.6.0-rc7.

To clarify, everything else seems to work with current torvalds/master, it's just HDMI audio that's missing.

[Chewi]

As you see in the source there is huge amount (buggy) code for hdmi audio. It takes many cpu cycles and you want everything for FPS, so use analog audio output of your motherboard. With my LG L246Wh monitor I need to set in the kernel command line to amdgpu.audio=0 to save 18 seconds of boot time.

I've used HDMI audio for a few years now and I'm not about to sacrifice it. I have a high end AV unit attached to it and I want to get 8 channel LPCM output from games. For the moment, I've hooked up an coaxial S/PDIF connection to the motherboard but that can't do 8 channel LPCM.

Also I've never noticed any CPU usage from HDMI audio. I have gkrellm permanently sitting on the left of my screen so I would notice.