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From: Doug Anderson <>
To: Rob Herring <>
Cc: Andrzej Hajda <>,
	Neil Armstrong <>,
	Laurent Pinchart <>,
	Jonas Karlman <>, Sam Ravnborg <>,
	Stanislav Lisovskiy <>,
	Lyude Paul <>,
	Thierry Reding <>,
	Stephen Boyd <>,
	Bjorn Andersson <>,
	linux-arm-msm <>,
	Maarten Lankhorst <>,
	Linus W <>,
	dri-devel <>,
	Rob Clark <>,
	Steev Klimaszewski <>,
	Daniel Vetter <>, David Airlie <>,
	Thierry Reding <>,
	"" <>
Subject: Re: [PATCH v7 02/10] dt-bindings: display: simple: List hpd properties in panel-simple
Date: Tue, 18 May 2021 06:58:16 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>


On Tue, May 18, 2021 at 5:42 AM Rob Herring <> wrote:
> On Mon, May 17, 2021 at 3:09 PM Douglas Anderson <> wrote:
> >
> > These are described in panel-common.yaml but if I don't list them in
> > panel-simple then I get yells when running 'dt_binding_check' in a
> > future patch. List them along with other properties that seem to be
> > listed in panel-simple for similar reasons.
> If you have HPD, is it still a simple panel? I don't see this as an
> omission because the use of these properties for simple panels was
> never documented IIRC.

I would say so. It is currently supported by panel-simple in Linux. Of
course, you could make the argument that panel-simple is no longer
really "simple" because of things like this...

I guess I'd say this: I believe that the HPD properties eventually
belong in the generic "edp-panel" that I'm still planning to post (and
which will be based on this series). I justified that previously [1]
by talking about the fact that there's a single timing diagram that
(as far as I've been able to tell) is fairly universal in panel specs.
It's a complicated timing diagram showing some two dozen timings (and
includes HPD!), but if you support all the timings then you've
supported pretty much all panels. IMO the original intent of
"simple-panel" was to specify a panel that's just like all the other
panels w/ a few parameters.

NOTE: I'd also say that for nearly all eDP panels HPD is important,
but in many designs HPD is handled "magically" and not specified in
the device tree. This is because it goes to a dedicated location on
the eDP controller / bridge chip. I added the HPD GPIO support (and
no-hpd) to simple-panel because my bridge chip has a fairly useless
HPD line and we don't use it. Even though the fact that we need the
HPD specified like this is a function of our bridge chip, back in the
day I was told that the property belonged in the panel and so that's
where it lives.

> Not saying we can't add them, but justify it as an addition, not just
> fixing a warning.

Sure, I'll beef up the commit message.

> > Signed-off-by: Douglas Anderson <>
> > ---
> > I didn't spend tons of time digging to see if there was supposed to be
> > a better way of doing this. If there is, feel free to yell.
> That's the right way to do it unless you want to allow all common
> properties, then we'd use unevaluatedProperties instead of
> additionalProperties.

Ah, perfect. Thanks!



  reply	other threads:[~2021-05-18 13:58 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-17 20:08 [PATCH v7 00/10] drm: Fix EDID reading on ti-sn65dsi86 by introducing the DP AUX bus Douglas Anderson
2021-05-17 20:08 ` [PATCH v7 01/10] drm/panel: panel-simple: Add missing pm_runtime_dont_use_autosuspend() calls Douglas Anderson
2021-05-24 20:22   ` Laurent Pinchart
2021-05-24 21:08     ` Doug Anderson
2021-05-17 20:08 ` [PATCH v7 02/10] dt-bindings: display: simple: List hpd properties in panel-simple Douglas Anderson
2021-05-18 12:41   ` Rob Herring
2021-05-18 13:58     ` Doug Anderson [this message]
2021-05-22 10:38       ` Linus Walleij
2021-05-17 20:09 ` [PATCH v7 03/10] dt-bindings: drm/bridge: ti-sn65dsi86: Add aux-bus child Douglas Anderson
2021-05-19 20:01   ` Rob Herring
2021-05-19 21:06     ` Doug Anderson
2021-05-20 13:25       ` Rob Herring
2021-05-17 20:09 ` [PATCH v7 04/10] drm: Introduce the DP AUX bus Douglas Anderson
2021-05-22 10:34   ` Linus Walleij
2021-05-17 20:09 ` [PATCH v7 05/10] drm/panel: panel-simple: Allow panel-simple be a DP AUX endpoint device Douglas Anderson
2021-05-17 20:09 ` [PATCH v7 06/10] drm/panel: panel-simple: Stash DP AUX bus; allow using it for DDC Douglas Anderson
2021-05-17 20:09 ` [PATCH v7 07/10] drm/bridge: ti-sn65dsi86: Promote the AUX channel to its own sub-dev Douglas Anderson
2021-05-17 20:09 ` [PATCH v7 08/10] drm/bridge: ti-sn65dsi86: Add support for the DP AUX bus Douglas Anderson
2021-05-22 10:35   ` Linus Walleij
2021-05-24 20:29   ` Lyude Paul
2021-05-17 20:09 ` [PATCH v7 09/10] drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC Douglas Anderson
2021-05-17 20:09 ` [PATCH v7 10/10] arm64: dts: qcom: sc7180-trogdor: Move panel under the bridge chip Douglas Anderson
2021-05-22 10:40   ` Linus Walleij
2021-05-19 21:41 ` [PATCH v7 00/10] drm: Fix EDID reading on ti-sn65dsi86 by introducing the DP AUX bus Lyude Paul
2021-05-21 23:07 ` Lyude Paul
2021-05-24 15:14   ` Doug Anderson

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