linux-kernel - Re: [PATCH v7 2/9] drm: Support per-plane async flip configuration

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Message-ID: <CAA8EJpqM4iaG3PKM5c0Op7Y7c1SRDrOCk_oOnwG8YfdCxC8w6g@mail.gmail.com>
Date: Tue, 18 Jun 2024 13:07:33 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Jani Nikula <jani.nikula@...ux.intel.com>
Cc: André Almeida <andrealmeid@...lia.com>, 
	dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	nouveau@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org, 
	kernel-dev@...lia.com, Melissa Wen <mwen@...lia.com>, alexander.deucher@....com, 
	christian.koenig@....com, Simon Ser <contact@...rsion.fr>, 
	Pekka Paalanen <ppaalanen@...il.com>, daniel@...ll.ch, Daniel Stone <daniel@...ishbar.org>, 
	Marek Olšák <maraeo@...il.com>, 
	Dave Airlie <airlied@...il.com>, ville.syrjala@...ux.intel.com, 
	Xaver Hugl <xaver.hugl@...il.com>, Joshua Ashton <joshua@...ggi.es>, 
	Michel Dänzer <michel.daenzer@...lbox.org>, 
	Sam Ravnborg <sam@...nborg.org>, Boris Brezillon <bbrezillon@...nel.org>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Nicolas Ferre <nicolas.ferre@...rochip.com>, 
	Alexandre Belloni <alexandre.belloni@...tlin.com>, Claudiu Beznea <claudiu.beznea@...on.dev>, 
	Rodrigo Vivi <rodrigo.vivi@...el.com>, Karol Herbst <kherbst@...hat.com>, 
	Lyude Paul <lyude@...hat.com>
Subject: Re: [PATCH v7 2/9] drm: Support per-plane async flip configuration

On Tue, 18 Jun 2024 at 12:38, Jani Nikula <jani.nikula@...ux.intel.com> wrote:
>
> On Tue, 18 Jun 2024, André Almeida <andrealmeid@...lia.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: André Almeida <andrealmeid@...lia.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