From: Boris Brezillon <boris.brezillon@collabora.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
dri-devel@lists.freedesktop.org,
Nikita Yushchenko <nikita.yoush@cogentembedded.com>,
Mark Rutland <mark.rutland@arm.com>,
Jernej Skrabec <jernej.skrabec@siol.net>,
Neil Armstrong <narmstrong@baylibre.com>,
Andrey Smirnov <andrew.smirnov@gmail.com>,
Jonas Karlman <jonas@kwiboo.se>, Rob Herring <robh+dt@kernel.org>,
Andrzej Hajda <a.hajda@samsung.com>,
devicetree@vger.kernel.org,
Thierry Reding <thierry.reding@gmail.com>,
intel-gfx-trybot@lists.freedesktop.org, kernel@collabora.com,
Chris Healy <cphealy@gmail.com>
Subject: Re: [PATCH v10 08/12] drm/bridge: lvds-codec: Implement basic bus format negotiation
Date: Tue, 25 Feb 2020 09:44:23 +0100 [thread overview]
Message-ID: <20200225094423.6fd2d6d5@collabora.com> (raw)
In-Reply-To: <20200225061543.GA9944@ravnborg.org>
On Tue, 25 Feb 2020 07:15:43 +0100
Sam Ravnborg <sam@ravnborg.org> wrote:
> Hi Boris/Laurent.
>
> > > +
> > > + err = of_property_read_u32(np, "bus-width", &input_bus_width);
> > > + of_node_put(np);
> > > +
> > > + if (err) {
> > > + lvds_codec->input_fmt = MEDIA_BUS_FMT_FIXED;
> > > + } else if (input_bus_width == 18) {
> > > + lvds_codec->input_fmt = MEDIA_BUS_FMT_RGB666_1X18;
> > > + } else if (input_bus_width == 24) {
> > > + lvds_codec->input_fmt = MEDIA_BUS_FMT_RGB888_1X24;
> > > + } else {
> > > + dev_dbg(dev, "unsupported bus-width value %u on port 0\n",
> > > + input_bus_width);
> > > + return -ENOTSUPP;
> >
> > ENOTSUPP is "Operation not supported", I'd go for -EINVAL.
> >
> > > + }
> >
> > Doesn't this apply to LVDS encoders only ? For LVDS decoders I don't
> > think we want to report an RGB format on the input.
>
> In panel-lvds we use the property "data-mapping" for the same purpose.
> To specify the MEDIA_BUS format.
I started with data-mapping, and was told (by Laurent IIRC) that
bus-width would be more appropriate for a DPI (AKA RGB) bus. I think it
has to do with the fact that fully-parallel buses always have one color
bit per-signal, while serial or partially-parallel buses can have
several color-bits per-signal, the assignment being described by this
'data-mapping' property. This being said, I can see a case where
data-mapping would be needed for DPI buses => RGB component ordering. A
24bit bus does not distinguish between RGB888 and BGR888.
>
> It would be good to standardize on the same property, and maybe have the
> same binding descriptions for all.
As for the standardization, I'm all for it, but let's do that in a
second step, please.
next prev parent reply other threads:[~2020-02-25 8:44 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 13:55 [PATCH v10 00/12] drm: Add support for bus-format negotiation Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 01/12] drm/bridge: Add a drm_bridge_state object Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 02/12] drm/rcar-du: Plug atomic state hooks to the default implementation Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 03/12] drm/bridge: analogix: " Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 04/12] drm/bridge: Patch atomic hooks to take a drm_bridge_state Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 05/12] drm/bridge: Add an ->atomic_check() hook Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 06/12] drm/bridge: Add the necessary bits to support bus format negotiation Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 07/12] drm/imx: pd: Use bus format/flags provided by the bridge when available Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 08/12] drm/bridge: lvds-codec: Implement basic bus format negotiation Boris Brezillon
2020-02-24 23:03 ` Laurent Pinchart
2020-02-25 6:15 ` Sam Ravnborg
2020-02-25 8:44 ` Boris Brezillon [this message]
2020-01-28 13:55 ` [PATCH v10 09/12] dt-bindings: display: bridge: lvds-codec: Add new bus-width prop Boris Brezillon
2020-01-31 17:12 ` Sam Ravnborg
2020-01-31 17:23 ` Boris Brezillon
2020-02-24 22:31 ` Laurent Pinchart
2020-02-25 9:13 ` Boris Brezillon
2020-03-09 10:35 ` Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 10/12] drm/bridge: panel: Propage bus format/flags Boris Brezillon
2020-01-31 17:25 ` Boris Brezillon
2020-02-24 22:34 ` Laurent Pinchart
2020-02-25 8:45 ` Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 11/12] drm/panel: simple: Fix the lt089ac29000 bus_format Boris Brezillon
2020-01-28 13:55 ` [PATCH v10 12/12] ARM: dts: imx: imx51-zii-rdu1: Fix the display pipeline definition Boris Brezillon
2020-01-31 15:42 ` [PATCH v10 00/12] drm: Add support for bus-format negotiation Boris Brezillon
2020-01-31 16:51 ` Sam Ravnborg
2020-01-31 18:08 ` Daniel Vetter
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