[PATCH] drm/amdgpu: fix the ib test hang when gfx is in "idle" state

[Huang Rui]

On Mon, Apr 23, 2018 at 05:52:28PM +0800, Huang Rui wrote:
> On Fri, Apr 20, 2018 at 05:59:16PM +0800, Koenig, Christian wrote:
> > Am 20.04.2018 um 11:40 schrieb Huang Rui:
> > > "aaabaf4   drm/amdgpu: defer test IBs on the rings at boot (V3)"
> > > Above patch defers the execution of gfx/compute ib tests. However, at that time,
> > > the gfx may already go into idle state. If "idle" gfx receives command
> > > submission, it will get hang in the system. So we must add is_gfx_on checking at
> > > start of ib tests.
> > 
> > Do I see that right that you just skip the IB test when the GFX block is 
> > already turned of? In this case that would be a clear NAK.
> > 
> > BTW: How do you detect that we need to turn GFX on again?
> 
> Christian, I know point. But there is a hang issue if we would like try to
> disable/enable gfxoff with SMC message at runtime. Actually, I am trying to
> find a good sequence to fix it. After that, I can even expose an debugfs
> interface to configure that. So I have to skip the test for the moment when
> gfx is in "idle".
> 

And in normal case, driver won't explicitly turn on/off the gfx. RLC
firmware will handle it.

Thanks,
Ray