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

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Message-ID: <caa69e8e-f330-d819-e8cd-7b06aa8eb855@amd.com>
Date:   Wed, 21 Jun 2023 09:42:25 +0200
From:   Christian König <christian.koenig@....com>
To:     André Almeida <andrealmeid@...lia.com>,
        dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Cc:     kernel-dev@...lia.com, alexander.deucher@....com,
        pierre-eric.pelloux-prayer@....com,
        Simon Ser <contact@...rsion.fr>,
        Rob Clark <robdclark@...il.com>,
        Pekka Paalanen <ppaalanen@...il.com>,
        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

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.

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

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(-)
>