Re: [PATCH v3 18/21] drm/bridge: panel: Propage bus format/flags

From: Boris Brezillon <boris.brezillon@collabora.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org,
	Lucas Stach <l.stach@pengutronix.de>,
	Chris Healy <cphealy@gmail.com>,
	Andrey Smirnov <andrew.smirnov@gmail.com>,
	Nikita Yushchenko <nikita.yoush@cogentembedded.com>,
	kernel@collabora.com, Daniel Vetter <daniel@ffwll.ch>,
	Inki Dae <inki.dae@samsung.com>,
	Joonyoung Shim <jy0922.shim@samsung.com>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	Rob Clark <robdclark@gmail.com>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v3 18/21] drm/bridge: panel: Propage bus format/flags
Date: Wed, 22 Jan 2020 10:27:19 +0100	[thread overview]
Message-ID: <20200122102719.1149f6f6@collabora.com> (raw)
In-Reply-To: <20191203101730.GP4730@pendragon.ideasonboard.com>

Hi Laurent,

Sorry for the late reply.

On Tue, 3 Dec 2019 12:17:30 +0200
Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:

> Hi Boris,
> 
> Thank you for the patch.
> 
> On Wed, Oct 23, 2019 at 05:45:09PM +0200, Boris Brezillon wrote:
> > So that the previous bridge element in the chain knows which input
> > format the panel bridge expects.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > ---
> > Changes in v3:
> > * Adjust things to match the new bus-format negotiation approach
> > * Use drm_atomic_helper_bridge_propagate_bus_fmt
> > * Don't implement ->atomic_check() (the core now takes care of bus
> >   flags propagation)
> > 
> > Changes in v2:
> > * Adjust things to match the new bus-format negotiation approach
> > ---
> >  drivers/gpu/drm/bridge/panel.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
> > index f4e293e7cf64..a70c363a2bd0 100644
> > --- a/drivers/gpu/drm/bridge/panel.c
> > +++ b/drivers/gpu/drm/bridge/panel.c
> > @@ -127,6 +127,7 @@ static const struct drm_bridge_funcs panel_bridge_bridge_funcs = {
> >  	.enable = panel_bridge_enable,
> >  	.disable = panel_bridge_disable,
> >  	.post_disable = panel_bridge_post_disable,
> > +	.atomic_get_input_bus_fmts = drm_atomic_helper_bridge_propagate_bus_fmt,  
> 
> Shouldn't the format be retrieved from the panel instead of from the
> connector ? We're moving towards removing connector creation from
> bridges, so I think it would be more future-proof.

Right now the panel bus_format is not exposed by the drm_panel
abstraction (only panel_simple have access to this information through
their panel_desc). I'd rather not add new things to this series so I'm
in favor of keeping the current implementation, but I add this idea
(expose bus format through the drm_panel abstraction) to my TODO list.

Thanks,

Boris