Re: [PATCH 2/3] dt-bindings: drm/bridge: ti-sn65dsi86: Add hpd-gpios to the bindings

From: Stephen Boyd <swboyd@chromium.org>
To: Douglas Anderson <dianders@chromium.org>,
	Laurent.pinchart@ideasonboard.com, a.hajda@samsung.com,
	airlied@linux.ie, daniel@ffwll.ch, narmstrong@baylibre.com,
	robh+dt@kernel.org, spanda@codeaurora.org
Cc: jonas@kwiboo.se, bjorn.andersson@linaro.org,
	devicetree@vger.kernel.org, jeffrey.l.hugo@gmail.com,
	jernej.skrabec@siol.net, linux-arm-msm@vger.kernel.org,
	robdclark@chromium.org, dri-devel@lists.freedesktop.org,
	Douglas Anderson <dianders@chromium.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: drm/bridge: ti-sn65dsi86: Add hpd-gpios to the bindings
Date: Wed, 15 Apr 2020 12:53:02 -0700	[thread overview]
Message-ID: <158698038289.105027.2860892334897893887@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20200415084758.2.Ic98f6622c60a1aa547ed85781f2c3b9d3e56b734@changeid>

Quoting Douglas Anderson (2020-04-15 08:48:40)
> Allow people to specify to use a GPIO for hot-plug-detect.  Add an
> example.
> 
> NOTE: The current patch adding support for hpd-gpios to the Linux
> driver for hpd-gpios only adds enough support to the driver so that
> the bridge can use one of its own GPIOs.  The bindings, however, are
> written generically.
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 
>  .../bindings/display/bridge/ti,sn65dsi86.yaml          | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
> index 8cacc6db33a9..554bfd003000 100644
> --- a/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
> +++ b/Documentation/devicetree/bindings/display/bridge/ti,sn65dsi86.yaml
> @@ -60,6 +60,10 @@ properties:
>      const: 1
>      description: See ../../pwm/pwm.yaml for description of the cell formats.
>  
> +  hpd-gpios:
> +    maxItems: 1
> +    description: If present use the given GPIO for hot-plug-detect.

Shouldn't this go in the panel node? And the panel driver should get the
gpio and poll it after powering up the panel? Presumably that's why we
have the no-hpd property in the simple panel binding vs. putting it here
in the bridge.