linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Rob Herring <robh@kernel.org>
To: Douglas Anderson <dianders@chromium.org>
Cc: Sean Paul <seanpaul@chromium.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Sandeep Panda <spanda@codeaurora.org>,
	linux-arm-msm@vger.kernel.org,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	jsanka@codeaurora.org, ryandcase@chromium.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH 1/6] dt-bindings: drm/panel: simple: Add no-hpd property
Date: Thu, 25 Oct 2018 14:28:35 -0500	[thread overview]
Message-ID: <20181025192835.GA30136@bogus> (raw)
In-Reply-To: <20181022204639.8558-1-dianders@chromium.org>

On Mon, Oct 22, 2018 at 01:46:34PM -0700, Douglas Anderson wrote:
> Some eDP panels that are designed to be always connected to a board
> use their HPD signal to signal that they've finished powering on and
> they're ready to be talked to.
> 
> However, for various reasons it's possible that the HPD signal from
> the panel isn't actually hooked up.  In the case where the HPD isn't
> hooked up you can look at the timing diagram on the panel datasheet
> and insert a delay for the maximum amount of time that the HPD might
> take to come up.
> 
> Let's add a property in the device tree for this concept.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 
>  .../devicetree/bindings/display/panel/simple-panel.txt         | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/panel/simple-panel.txt b/Documentation/devicetree/bindings/display/panel/simple-panel.txt
> index 45a457ad38f0..b2b872c710f2 100644
> --- a/Documentation/devicetree/bindings/display/panel/simple-panel.txt
> +++ b/Documentation/devicetree/bindings/display/panel/simple-panel.txt
> @@ -11,6 +11,9 @@ Optional properties:
>  - ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing
>  - enable-gpios: GPIO pin to enable or disable the panel
>  - backlight: phandle of the backlight device attached to the panel
> +- no-hpd: This panel is supposed to communicate that it's ready via HPD
> +  (hot plug detect) signal, but the signal isn't hooked up so we should
> +  hardcode the max delay from the panel spec when powering up the panel.

If we have this here, then we should also have hpd-gpios defined here as 
where we describe a connection we should also describe no connection.

Now, hpd-gpios is a bit of a mess being defined in both connector nodes 
and bridge (HDMI/DP) nodes. I think that is just history pre-dating 
connector nodes. Connector nodes are now the preferred place. Connector 
nodes and panel nodes are essentially the same thing (the endpoint of 
display pipeline).

That being said, this patch is fine as is.

Reviewed-by: Rob Herring <robh@kernel.org>

Rob

      parent reply	other threads:[~2018-10-25 19:28 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-22 20:46 Douglas Anderson
2018-10-22 20:46 ` [PATCH 2/6] drm/panel: simple: Support panels with HPD where HPD isn't connected Douglas Anderson
2018-10-25 18:08   ` Sean Paul
2018-10-22 20:46 ` [PATCH 3/6] drm/panel: simple: Add "no-hpd" delay for Innolux TV123WAM Douglas Anderson
2018-10-22 20:46 ` [PATCH 4/6] drm/bridge: ti-sn65dsi86: Remove the mystery delay Douglas Anderson
2018-10-25 18:10   ` Sean Paul
2018-10-22 20:46 ` [PATCH 5/6] drm/panel: simple: Innolux TV123WAM is actually P120ZDG-BF1 Douglas Anderson
2018-10-25 18:13   ` Sean Paul
2018-10-25 18:45     ` Doug Anderson
2018-10-25 19:25       ` Abhinav Kumar
2018-10-25 22:24     ` Doug Anderson
2018-10-26 14:38       ` Sean Paul
2018-10-22 20:46 ` [PATCH 6/6] dt-bindings: " Douglas Anderson
2018-10-25 18:15   ` Sean Paul
2018-10-25 19:49   ` Rob Herring
2018-10-25 18:06 ` [PATCH 1/6] dt-bindings: drm/panel: simple: Add no-hpd property Sean Paul
2018-10-25 19:28 ` Rob Herring [this message]

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:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

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

  git send-email \
    --in-reply-to=20181025192835.GA30136@bogus \
    --to=robh@kernel.org \
    --cc=airlied@linux.ie \
    --cc=devicetree@vger.kernel.org \
    --cc=dianders@chromium.org \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=jsanka@codeaurora.org \
    --cc=laurent.pinchart@ideasonboard.com \
    --cc=linux-arm-msm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=ryandcase@chromium.org \
    --cc=seanpaul@chromium.org \
    --cc=spanda@codeaurora.org \
    --cc=thierry.reding@gmail.com \
    --subject='Re: [PATCH 1/6] dt-bindings: drm/panel: simple: Add no-hpd property' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

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).