[PATCH RFC v4 01/16] drm: Add drm_minor_for_each

Daniel Vetter daniel at ffwll.ch
Fri Sep 6 15:36:02 UTC 2019

On Fri, Sep 6, 2019 at 5:29 PM Tejun Heo <tj at kernel.org> wrote:
> Hello,
> On Wed, Sep 04, 2019 at 10:54:34AM +0200, Daniel Vetter wrote:
> > Anyway, I don't think reusing the drm_minor registration makes sense,
> > since we want to be on the drm_device, not on the minor. Which is a bit
> > awkward for cgroups, which wants to identify devices using major.minor
> > pairs. But I guess drm is the first subsystem where 1 device can be
> > exposed through multiple minors ...
> >
> > Tejun, any suggestions on this?
> I'm not extremely attached to maj:min.  It's nice in that it'd be
> consistent with blkcg but it already isn't the nicest of identifiers
> for block devices.  If using maj:min is reasonably straight forward
> for gpus even if not perfect, I'd prefer going with maj:min.
> Otherwise, please feel free to use the ID best for GPUs - hopefully
> something which is easy to understand, consistent with IDs used
> elsewhere and easy to build tooling around.

Block devices are a great example I think. How do you handle the
partitions on that? For drm we also have a main minor interface, and
then the render-only interface on drivers that support it. So if blkcg
handles that by only exposing the primary maj:min pair, I think we can
go with that and it's all nicely consistent.
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

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