Nouveau - Jun 2024 - [PATCH v7 2/9] drm: Support per-plane async flip configuration

On Tue, 18 Jun 2024, Andr? Almeida <andrealmeid at igalia.com>
wrote:
> Drivers have different capabilities on what plane types they can or
> cannot perform async flips. Create a plane::async_flip field so each
> driver can choose which planes they allow doing async flips.
>
> Signed-off-by: Andr? Almeida <andrealmeid at igalia.com>
> ---
>  include/drm/drm_plane.h | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> index 9507542121fa..0bebc72af5c3 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -786,6 +786,11 @@ struct drm_plane {
>  	 * @kmsg_panic: Used to register a panic notifier for this plane
>  	 */
>  	struct kmsg_dumper kmsg_panic;
> +
> +	/**
> +	 * @async_flip: indicates if a plane can do async flips
> +	 */
When is it okay to set or change the value of this member?

If you don't document it, people will find creative uses for this.

BR,
Jani.

> +	bool async_flip;
>  };
>  
>  #define obj_to_plane(x) container_of(x, struct drm_plane, base)
-- 
Jani Nikula, Intel

On Tue, 18 Jun 2024 at 12:38, Jani Nikula <jani.nikula at linux.intel.com>
wrote:
>
> On Tue, 18 Jun 2024, Andr? Almeida <andrealmeid at igalia.com> wrote:
> > Drivers have different capabilities on what plane types they can or
> > cannot perform async flips. Create a plane::async_flip field so each
> > driver can choose which planes they allow doing async flips.
> >
> > Signed-off-by: Andr? Almeida <andrealmeid at igalia.com>
> > ---
> >  include/drm/drm_plane.h | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> > index 9507542121fa..0bebc72af5c3 100644
> > --- a/include/drm/drm_plane.h
> > +++ b/include/drm/drm_plane.h
> > @@ -786,6 +786,11 @@ struct drm_plane {
> >        * @kmsg_panic: Used to register a panic notifier for this plane
> >        */
> >       struct kmsg_dumper kmsg_panic;
> > +
> > +     /**
> > +      * @async_flip: indicates if a plane can do async flips
> > +      */
>
> When is it okay to set or change the value of this member?
>
> If you don't document it, people will find creative uses for this.
Maybe it's better to have a callback instead of a static field? This
way it becomes clear that it's only relevant at the time of the
atomic_check().
> > +     bool async_flip;
> >  };
> >
> >  #define obj_to_plane(x) container_of(x, struct drm_plane, base)
>
> --
> Jani Nikula, Intel


-- 
With best wishes
Dmitry