linux-kernel - Re: [PATCH v6 2/8] drm: Support per-plane async flip configuration

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Date: Fri, 14 Jun 2024 20:32:27 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: André Almeida <andrealmeid@...lia.com>
Cc: 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>, 
	Jani Nikula <jani.nikula@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>, 
	Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>
Subject: Re: [PATCH v6 2/8] drm: Support per-plane async flip configuration

On Fri, Jun 14, 2024 at 12:35:29PM GMT, André Almeida 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>
> ---
>  drivers/gpu/drm/drm_atomic_uapi.c | 4 ++--
>  include/drm/drm_plane.h           | 5 +++++
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index 2e1d9391febe..ed1af3455477 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -1079,9 +1079,9 @@ int drm_atomic_set_property(struct drm_atomic_state *state,
>  			break;
>  		}
>  
> -		if (async_flip && plane_state->plane->type != DRM_PLANE_TYPE_PRIMARY) {
> +		if (async_flip && !plane->async_flip) {

So, after this patch async flips becomes disabled until the driver
enables that manually. Whether that's desired or not is a separate
topic, but this definitely should be explicitly mentioned in the commit
message.

>  			drm_dbg_atomic(prop->dev,
> -				       "[OBJECT:%d] Only primary planes can be changed during async flip\n",
> +				       "[PLANE:%d] does not support async flips\n",
>  				       obj->id);
>  			ret = -EINVAL;
>  			break;
> 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
> +	 */
> +	bool async_flip;
>  };
>  
>  #define obj_to_plane(x) container_of(x, struct drm_plane, base)
> -- 
> 2.45.2
> 

-- 
With best wishes
Dmitry