It comes from amdgpu_query_gpu_info_init()
for (i = 0; i < (int)dev->info.num_shader_engines; i++) {
unsigned instance = (i << AMDGPU_INFO_MMR_SE_INDEX_SHIFT) |
(AMDGPU_INFO_MMR_SH_INDEX_MASK <<
AMDGPU_INFO_MMR_SH_INDEX_SHIFT);
r = amdgpu_read_mm_registers(dev, 0x263d, 1, instance, 0,
&dev->info.backend_disable[i]);
This effectively reads from 0/* where the kernel adds the instance of * so it's 0/*/*. That line was last changed by Alex
0936139536380 (Alex Deucher 2015-04-20 12:04:22 -0400 174) (AMDGPU_INFO_MMR_SH_INDEX_MASK <<
I still don't get why this is a reason to hit pause on the patch(es) though. They're root only, you can still not use * if you don't want to and furthermore I'm already using the write debugfs content (to debug waveforms).
Tom
________________________________
From: Michel Dänzer <michel.daenzer@xxxxxxxxxxx>
Sent: Tuesday, October 11, 2016 20:34
To: StDenis, Tom; Christian König
Cc: amd-gfx at lists.freedesktop.org
Subject: Re: [PATCH] drm/amd/amdgpu: Allow broadcast on debugfs read (v2)
On 11/10/16 09:32 PM, StDenis, Tom wrote:
> It's used by the UMD though they read from 0/*/* when reading the
> RASTER_CONFIG registers (which may be a bug...)
We should probably clarify what userspace is trying to do there, and
whether the hardware actually does that.
--
Earthling Michel Dänzer | http://www.amd.com
Graphics, Processors and Immersive VR Solutions | AMD <http://www.amd.com/>
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