archive mirror
 help / color / mirror / Atom feed
From: Douglas Anderson <>
To: Andrzej Hajda <>,
	Neil Armstrong <>,
	Laurent Pinchart <>,
	Jonas Karlman <>, Sam Ravnborg <>
Cc: Linus W <>,,
	Maarten Lankhorst <>,
	Stanislav Lisovskiy <>,
	Steev Klimaszewski <>,,
	Bjorn Andersson <>,
	Thierry Reding <>,
	Lyude Paul <>,,
	Stephen Boyd <>,
	Douglas Anderson <>,
	Rob Herring <>, Daniel Vetter <>,
	David Airlie <>, Rob Herring <>,
	Thierry Reding <>,,
Subject: [PATCH v9 01/11] dt-bindings: display: simple: List hpd properties in panel-simple
Date: Mon,  7 Jun 2021 10:05:45 -0700	[thread overview]
Message-ID: <20210607100234.v9.1.Ieb731d23680db4700cc41fe51ccc73ba0b785fb7@changeid> (raw)
In-Reply-To: <>

The HPD (Hot Plug Detect) signal is present in many (probably even
"most") eDP panels. For eDP, this signal isn't actually used for
detecting hot-plugs of the panel but is more akin to a "panel ready"
signal. After you provide power to the panel, panel timing diagrams
typically say that you should wait for HPD to be asserted (or wait a
fixed amount of time) before talking to the panel.

The panel-simple bindings describes many eDP panels and many of these
panels provide the HPD signal. We should add the HPD-related
properties to the panel-simple bindings. The HPD properties are
actually defined in panel-common.yaml, so adding them here just
documents that they are OK for panels handled by the panel-simple

NOTE: whether or not we'd include HPD properties in the panel node is
more a property of the board design than the panel itself. For most
boards using these eDP panels everything "magically" works without
specifying any HPD properties and that's been why we haven't needed to
allow the HPD properties earlier. On these boards the HPD signal goes
directly to a dedicated "HPD" input to the eDP controller and this
connection doesn't need to be described in the device tree. The only
time the HPD properties are needed in the device tree are if HPD is
hooked up to a GPIO or if HPD is normally on the panel but isn't used
on a given board. That means that if we don't allow the HPD properties
in panel-simple then one could argue that we've got to boot all eDP
panels (or at least all those that someone could conceivably put on a
system where HPD goes to a GPIO or isn't hooked up) from panel-simple.

Signed-off-by: Douglas Anderson <>
Reviewed-by: Rob Herring <>

(no changes since v8)

Changes in v8:
- Explain better why HPD needs to be in panel-simple in commit msg.

Changes in v7:
- List hpd properties bindings patch new for v7.

 .../devicetree/bindings/display/panel/panel-simple.yaml         | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/panel/panel-simple.yaml b/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
index b3797ba2698b..4a0a5e1ee252 100644
--- a/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
+++ b/Documentation/devicetree/bindings/display/panel/panel-simple.yaml
@@ -298,6 +298,8 @@ properties:
   enable-gpios: true
   port: true
   power-supply: true
+  no-hpd: true
+  hpd-gpios: true
 additionalProperties: false

  reply	other threads:[~2021-06-07 17:06 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-07 17:05 [PATCH v9 00/11] drm: Fix EDID reading on ti-sn65dsi86 by introducing the DP AUX bus Douglas Anderson
2021-06-07 17:05 ` Douglas Anderson [this message]
2021-06-07 17:05 ` [PATCH v9 02/11] dt-bindings: drm: Introduce " Douglas Anderson
2021-06-09 11:05   ` Linus Walleij
2021-06-07 17:05 ` [PATCH v9 03/11] dt-bindings: drm/bridge: ti-sn65dsi86: Add aux-bus child Douglas Anderson
2021-06-09 11:05   ` Linus Walleij
2021-06-07 17:05 ` [PATCH v9 04/11] drm: Introduce the DP AUX bus Douglas Anderson
2021-06-11 16:48   ` Lyude Paul
2021-06-07 17:05 ` [PATCH v9 05/11] drm/panel: panel-simple: Allow panel-simple be a DP AUX endpoint device Douglas Anderson
2021-06-07 17:05 ` [PATCH v9 06/11] drm/panel: panel-simple: Stash DP AUX bus; allow using it for DDC Douglas Anderson
2021-06-09 11:07   ` Linus Walleij
2021-06-07 17:05 ` [PATCH v9 07/11] drm/bridge: ti-sn65dsi86: Promote the AUX channel to its own sub-dev Douglas Anderson
2021-06-09 11:08   ` Linus Walleij
2021-06-07 17:05 ` [PATCH v9 08/11] drm/bridge: ti-sn65dsi86: Add support for the DP AUX bus Douglas Anderson
2021-06-07 17:05 ` [PATCH v9 09/11] drm/bridge: ti-sn65dsi86: Don't read EDID blob over DDC Douglas Anderson
2021-06-07 17:05 ` [PATCH v9 10/11] drm/bridge: ti-sn65dsi86: Improve probe errors with dev_err_probe() Douglas Anderson
2021-06-09 11:09   ` Linus Walleij
2021-06-07 17:05 ` [PATCH v9 11/11] arm64: dts: qcom: sc7180-trogdor: Move panel under the bridge chip Douglas Anderson
2021-06-09 15:27   ` Bjorn Andersson

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210607100234.v9.1.Ieb731d23680db4700cc41fe51ccc73ba0b785fb7@changeid \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).