linux-kernel - Re: [RFC PATCH v3 0/4] drm: Standardize device reset notification

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Message-ID: <195dd084-a97b-ef08-a221-e39ffcd7cc09@igalia.com>
Date:   Wed, 21 Jun 2023 12:06:58 -0300
From:   André Almeida <andrealmeid@...lia.com>
To:     Christian König <christian.koenig@....com>
Cc:     kernel-dev@...lia.com, alexander.deucher@....com,
        pierre-eric.pelloux-prayer@....com,
        Simon Ser <contact@...rsion.fr>, linux-kernel@...r.kernel.org,
        amd-gfx@...ts.freedesktop.org, Rob Clark <robdclark@...il.com>,
        Pekka Paalanen <ppaalanen@...il.com>,
        dri-devel@...ts.freedesktop.org, Daniel Vetter <daniel@...ll.ch>,
        Daniel Stone <daniel@...ishbar.org>,
        'Marek Olšák' <maraeo@...il.com>,
        Dave Airlie <airlied@...il.com>,
        Michel Dänzer <michel.daenzer@...lbox.org>,
        Samuel Pitoiset <samuel.pitoiset@...il.com>,
        Timur Kristóf <timur.kristof@...il.com>,
        Bas Nieuwenhuizen <bas@...nieuwenhuizen.nl>
Subject: Re: [RFC PATCH v3 0/4] drm: Standardize device reset notification

Em 21/06/2023 04:42, Christian König escreveu:
> Am 21.06.23 um 02:57 schrieb André Almeida:
>> Hi,
>>
>> This is a new version of the documentation for DRM device resets. As I 
>> dived
>> more in the subject, I started to believe that part of the problem was 
>> the lack
>> of a DRM API to get reset information from the driver. With an API, we 
>> can
>> better standardize reset queries, increase common code from both DRM 
>> and Mesa,
>> and make easier to write end-to-end tests.
>>
>> So this patchset, along with the documentation, comes with a new IOCTL 
>> and two
>> implementations of it for amdgpu and i915 (although just the former 
>> was really
>> tested). This IOCTL uses the "context id" to query reset information, 
>> but this
>> might be not generic enough to be included in a DRM API.
> 
> Well the basic problem with that is that we don't have a standard DRM 
> context defined.
> 
> If you want to do this you should probably start there first.

Any idea on how to start this? I tried to find previous work about that, 
but I didn't find.

> 
> Apart from that this looks like a really really good idea to me, 
> especially that we document the reset expectations.

I think I'll submit just the doc for the next version then, given that 
the IOCTL will need a lot of rework.

> 
> Regards,
> Christian.
> 
>>    At least for amdgpu,
>> this information is encapsulated by libdrm so one can't just call the 
>> ioctl
>> directly from the UMD as I was planning to, but a small refactor can 
>> be done to
>> expose the id. Anyway, I'm sharing it as it is to gather feedback if 
>> this seems
>> to work.
>>
>> The amdgpu and i915 implementations are provided as a mean of testing 
>> and as
>> exemplification, and not as reference code yet, as the goal is more 
>> about the
>> interface itself then the driver parts.
>>
>> For the documentation itself, after spending some time reading the 
>> reset path in
>> the kernel in Mesa, I decide to rewrite it to better reflect how it 
>> works, from
>> bottom to top.
>>
>> You can check the userspace side of the IOCLT here:
>>   Mesa: 
>> https://gitlab.freedesktop.org/andrealmeid/mesa/-/commit/cd687b22fb32c21b23596c607003e2a495f465
>>   libdrm: 
>> https://gitlab.freedesktop.org/andrealmeid/libdrm/-/commit/b31e5404893ee9a85d1aa67e81c2f58c1dac3c46
>>
>> For testing, I use this vulkan app that has an infinity loop in the 
>> shader:
>> https://github.com/andrealmeid/vulkan-triangle-v1
>>
>> Feedbacks are welcomed!
>>
>> Thanks,
>>         André
>>
>> v2: 
>> https://lore.kernel.org/all/20230227204000.56787-1-andrealmeid@igalia.com/
>> v1: 
>> https://lore.kernel.org/all/20230123202646.356592-1-andrealmeid@igalia.com/
>>
>> André Almeida (4):
>>    drm/doc: Document DRM device reset expectations
>>    drm: Create DRM_IOCTL_GET_RESET
>>    drm/amdgpu: Implement DRM_IOCTL_GET_RESET
>>    drm/i915: Implement DRM_IOCTL_GET_RESET
>>
>>   Documentation/gpu/drm-uapi.rst                | 51 ++++++++++++++++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c        |  4 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c       | 35 +++++++++++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.h       |  5 ++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c       |  1 +
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_job.c       | 12 +++-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_job.h       |  2 +
>>   drivers/gpu/drm/drm_debugfs.c                 |  2 +
>>   drivers/gpu/drm/drm_ioctl.c                   | 58 +++++++++++++++++++
>>   drivers/gpu/drm/i915/gem/i915_gem_context.c   | 18 ++++++
>>   drivers/gpu/drm/i915/gem/i915_gem_context.h   |  2 +
>>   .../gpu/drm/i915/gem/i915_gem_context_types.h |  2 +
>>   drivers/gpu/drm/i915/i915_driver.c            |  2 +
>>   include/drm/drm_device.h                      |  3 +
>>   include/drm/drm_drv.h                         |  3 +
>>   include/uapi/drm/drm.h                        | 21 +++++++
>>   include/uapi/drm/drm_mode.h                   | 15 +++++
>>   17 files changed, 233 insertions(+), 3 deletions(-)
>>
>