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

[Christian König]

Am 21.06.23 um 17:06 schrieb André Almeida:
> 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.

I'm not aware of any work in this area, maybe ping on the Mesa list as well.

Could be that someone looked into that but never send anything out.

> > 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.

Yeah, agree completely.

Thanks,
Christian.

> > 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@xxxxxxxxxx/
> > > v1: 
> > > https://lore.kernel.org/all/20230123202646.356592-1-andrealmeid@xxxxxxxxxx/
> > >
> > > 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(-)