Re: [PATCH] drm/amdgpu: select ARCH_HAS_HMM and ZONE_DEVICE option

From: Jerome Glisse <jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: "Kuehling, Felix" <Felix.Kuehling-5C7GfCeVMHo@public.gmane.org>
Cc: "Yang, Philip" <Philip.Yang-5C7GfCeVMHo@public.gmane.org>,
	"amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org"
	<amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org>
Subject: Re: [PATCH] drm/amdgpu: select ARCH_HAS_HMM and ZONE_DEVICE option
Date: Wed, 20 Feb 2019 17:12:44 -0500	[thread overview]
Message-ID: <20190220221243.GA29398@redhat.com> (raw)
In-Reply-To: <1dfb54a4-67bf-2e96-40f4-7bfe24284232-5C7GfCeVMHo@public.gmane.org>

On Wed, Feb 20, 2019 at 07:18:17PM +0000, Kuehling, Felix wrote:
> [+Jerome]
> 
> Why to we need ZONE_DEVICE. I didn't think this was needed for mirroring 
> CPU page tables to device page tables.
> 
> ARCH_HAS_HMM depends on (X86_64 || PPC64). Do we have some alternative 
> for ARM support?
> 
> Also, the name ARCH_HAS_HMM looks like it's meant to be selected by the 
> CPU architecture rather than any driver. Jerome, do you have any advice?

This patch is wrong you need to depend on ARCH_HAS_HMM and
select HMM_MIRROR you do not need to select ZONE_DEVICE

So it should look like:

config DRM_AMDGPU_USERPTR
	bool "Always enable userptr write support"
	depends on DRM_AMDGPU
	depends on ARCH_HAS_HMM
	select HMM_MIRROR
	help
	  This option selects CONFIG_HMM and CONFIG_HMM_MIRROR if it
	  isn't already selected to enabled full userptr support.

I have not got around to work on amdgpu on that respect yet
but it is on my todo list unless someone else beat me to it :)

Cheers,
Jérôme

> 
> Thanks,
>    Felix
> 
> On 2019-02-20 1:56 p.m., Yang, Philip wrote:
> > Those options are needed to support HMM
> >
> > Change-Id: Ieb7bb3bcec07245d79a02793e6728228decc400a
> > Signed-off-by: Philip Yang <Philip.Yang@amd.com>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/Kconfig | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/Kconfig b/drivers/gpu/drm/amd/amdgpu/Kconfig
> > index 960a63355705..63f0542bc34b 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/Kconfig
> > +++ b/drivers/gpu/drm/amd/amdgpu/Kconfig
> > @@ -26,7 +26,9 @@ config DRM_AMDGPU_CIK
> >   config DRM_AMDGPU_USERPTR
> >   	bool "Always enable userptr write support"
> >   	depends on DRM_AMDGPU
> > +	select ARCH_HAS_HMM
> >   	select HMM_MIRROR
> > +	select ZONE_DEVICE
> >   	help
> >   	  This option selects CONFIG_HMM and CONFIG_HMM_MIRROR if it
> >   	  isn't already selected to enabled full userptr support.
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