[PATCH i-g-t] tests/kms_properties: drop immutability checks

[Daniel Stone]

Hi,

On Thu, 18 Jul 2024 at 11:01, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> On Wed, Jul 17, 2024 at 05:39:47PM +0300, Dmitry Baryshkov wrote:
> > Following the discussion on IRC, it is actually an error to require that
> > properties that can not be chaged are marked as immutable.
> >
> > First of all, it creates inconsistent uAPI. Some drivers might have an
> > immutable property, while others will have it mutable. Yes, there are
> > known examples for such behaviour (e.g. zpos), but they are clearly
> > documented in this way.
> >
> > Second, by the nature of the flag, the DRM_MODE_PROP_IMMUTABLE defines
> > more of the 'direction' of the property (whether it is set by the kernel
> > or it is expected to be set by the userspace) rather than simply states
> > that there is no way for the userspace to change the property.
> >
> > Drop the single-value-is-immutable tests.
>
> Makes sense, but we might drop some test coverage for the properties where
> we _do_ want the single value to be immutable. Like zpos.
>
> So I think at least a cursory audit of existing properties would be good,
> checking that the kerneldoc is accurate and then maybe limiting these
> checks here to properties which are documented to have this behaviour?
>
> I know that's a bunch more work, but I fear if we just drop this we only
> move from one a bit confusing state of the uapi to another one, without
> real improvements.
>
> Ofc if all the compositor folks tell me that this doesn't matter anyway,
> I'll shut up :-)

Weston doesn't care - the effect is the same for us whether it's
immutable or mutable-but-single-value.

CCed some other compositor people too.

Cheers,
Daniel