[Intel-gfx] [PATCH] drm/i915: disable set/get_tiling ioctl on gen12+

[Daniel Vetter]

On Wed, Sep 4, 2019 at 4:29 PM Daniel Vetter <daniel at ffwll.ch> wrote:
>
> On Tue, Sep 3, 2019 at 9:21 PM Souza, Jose <jose.souza at intel.com> wrote:
> >
> > On Thu, 2019-08-29 at 08:50 +0200, Daniel Vetter wrote:
> > > On Wed, Aug 28, 2019 at 08:31:27PM +0000, Souza, Jose wrote:
> > > > On Wed, 2019-08-28 at 21:13 +0100, Chris Wilson wrote:
> > > > > Quoting Souza, Jose (2019-08-28 21:11:53)
> > > > > > Reviewed-by: José Roberto de Souza <jose.souza at intel.com>
> > > > >
> > > > > It's using a non-standard for i915 error code, and get_tiling is
> > > > > not
> > > >
> > > > Huum should it use ENOTSUPP then?!
> > >
> > > https://dri.freedesktop.org/docs/drm/gpu/drm-uapi.html#recommended-ioctl-return-values
> > >
> > > Per above "feature not supported" -> EOPNOTSUPP.
> >
> > But like Chris said we are not using EOPNOTSUPP in i915,
> > i915_perf_open_ioctl() and other 2 perf ioctl uses ENOSUPP, should we
> > convert those to EOPNOTSUPP?
>
> $ git grep EOPNOTSUP -- drivers/gpu/drm/ | wc -l
> 114
> $ git grep ENOTSUP -- drivers/gpu/drm/ | wc -l
> 32

Note that most of the ENOTSUP is in drivers, for the drm core it's
even more clear:

$ git grep EOPNOTSUP -- drivers/gpu/drm/*c | wc -l
83
$ git grep ENOTSUP -- drivers/gpu/drm/*c | wc -l
5

Cheers, Daniel

> Plus i915_pmu.c also has a use of EOPNOTSUPP already.
>
> Furthermore the header for EOPNOTSUP has a pretty clear comment:
>
> /* Defined for the NFSv3 protocol */
>
> Above the entore block of error codes containing ENOTSUPP.
>
> So given all that, plus that we've decided to go with EOPNOTSUPP as
> the drm-wide recommendation: EOPNOTSUPP it is.
>
> If you disagree, I think there's a pretty substantial patch series for
> you to type and fix the docs and most users plus explain why we should
> use an nsf-specific error code (which isn't much worse than the
> abuse/reinterpretation we currently do, but still I think it's a bit
> more bending of errno code intentions).
>
> Cheers, Daniel
>
>
>
> >
> > >
> > > > > affected, it will always return LINEAR. You cannot set tiling as
> > > >
> > > > Following this set_tiling() LINEAR should be allowed too.
> > > > I prefer the current approach of returning error.
> > >
> > > I'm not seeing the value in keeping get_tiling supported. Either
> > > userspace
> > > still uses the legacy backhannel and dri2, in which case it needs to
> > > be
> > > fixed no matter what. Or it's using modifiers, in which case this is
> > > dead
> > > code. Only other user I can think of is takeover for fastboot, but if
> > > you
> > > get anything else than untiled it's also broken (we don't have an
> > > ioctl to
> > > read out the modifiers, heck even all the planes, there's no getfb2).
> > >
> > > So really not seeing the point in keeping that working.
> > > -Daniel
>
>
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch