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Date:   Tue, 13 Jun 2023 16:20:41 +0200
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Subject: Re: [PATCH drm-next v4 00/14] [RFC] DRM GPUVA Manager & Nouveau
 VM_BIND UAPI
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To:     Donald Robson <Donald.Robson@imgtec.com>
Cc:     "corbet@lwn.net" <corbet@lwn.net>,
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References: <20230606223130.6132-1-dakr@redhat.com>
 <f5723444623b41d58f93c3f0ab662e9b37105765.camel@imgtec.com>
From:   Danilo Krummrich <dakr@redhat.com>
Organization: RedHat
In-Reply-To: <f5723444623b41d58f93c3f0ab662e9b37105765.camel@imgtec.com>
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Hi Donald,

On 6/9/23 13:56, Donald Robson wrote:
> On Wed, 2023-06-07 at 00:31 +0200, Danilo Krummrich wrote:
>>
>> Christian König (1):
>>    drm: execution context for GEM buffers v4
>>
>> Danilo Krummrich (13):
>>    maple_tree: split up MA_STATE() macro
>>    drm: manager to keep track of GPUs VA mappings
> 
> I have tested the drm GPUVA manager as part of using it with our new
> driver.  The link below shows use of the drm_gpuva_sm_[un]map()
> functions.  I think this is based on the v3 patches, but I have also
> tried it locally using v4 patches.  We will be submitting this
> driver for review soon.

That's awesome - thank your for taking the effort!

> 
> https://gitlab.freedesktop.org/sarah-walker-imgtec/powervr/-/blob/dev/v3/drivers/gpu/drm/imagination/pvr_vm.c
> 
> In a previous incarnation, I used the drm_gpuva_insert() and
> drm_gpuva_remove() functions directly.  In some now abandoned work I
> used the drm_gpuva_sm_[un]map_ops_create() route.
> 
> The only problem I encountered along the way was the maple tree init
> issue already reported by Boris and fixed in v4.  One caveat - as
> our driver is a work in progress our testing is limited to certain
> Sascha Willem tests.
> 
> I did find it quite difficult to get the prealloc route with
> drm_gpuva_sm_[un]map() working.  I'm not sure to what degree this
> reflects me being a novice on matters DRM, but I did find myself
> wishing for more direction, even with Boris's help.

I'm definitely up improving the existing documentation. Anything in 
particular you think should be described in more detail?

- Danilo

> 
> Tested-by: Donald Robson <donald.robson@imgtec.com>
> 
>>    drm: debugfs: provide infrastructure to dump a DRM GPU VA space
>>    drm/nouveau: new VM_BIND uapi interfaces
>>    drm/nouveau: get vmm via nouveau_cli_vmm()
>>    drm/nouveau: bo: initialize GEM GPU VA interface
>>    drm/nouveau: move usercopy helpers to nouveau_drv.h
>>    drm/nouveau: fence: separate fence alloc and emit
>>    drm/nouveau: fence: fail to emit when fence context is killed
>>    drm/nouveau: chan: provide nouveau_channel_kill()
>>    drm/nouveau: nvkm/vmm: implement raw ops to manage uvmm
>>    drm/nouveau: implement new VM_BIND uAPI
>>    drm/nouveau: debugfs: implement DRM GPU VA debugfs
>>