linux-kernel - Re: [PATCH 2/2] drm: bridge: add enable gpio for display-connector

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Message-ID: <20251028154929.GA797@pendragon.ideasonboard.com>
Date: Tue, 28 Oct 2025 17:49:29 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Prahlad Valluru <venkata.valluru@....qualcomm.com>
Cc: David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Andrzej Hajda <andrzej.hajda@...el.com>,
	Neil Armstrong <neil.armstrong@...aro.org>,
	Robert Foss <rfoss@...nel.org>, Jonas Karlman <jonas@...boo.se>,
	Jernej Skrabec <jernej.skrabec@...il.com>,
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm: bridge: add enable gpio for display-connector

On Tue, Oct 28, 2025 at 08:56:50PM +0530, Prahlad Valluru wrote:
> In some cases, need gpio to be set for the connector
> enable. Add optional enable gpio to display-connector.
> 
> Signed-off-by: Prahlad Valluru <venkata.valluru@....qualcomm.com>
> ---
>  drivers/gpu/drm/bridge/display-connector.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/display-connector.c b/drivers/gpu/drm/bridge/display-connector.c
> index e9f16dbc9535..52f5e4175e64 100644
> --- a/drivers/gpu/drm/bridge/display-connector.c
> +++ b/drivers/gpu/drm/bridge/display-connector.c
> @@ -21,6 +21,7 @@ struct display_connector {
>  	struct drm_bridge	bridge;
>  
>  	struct gpio_desc	*hpd_gpio;
> +	struct gpio_desc	*enable_gpio;
>  	int			hpd_irq;
>  
>  	struct regulator	*supply;
> @@ -298,6 +299,12 @@ static int display_connector_probe(struct platform_device *pdev)
>  					     "Unable to retrieve HPD GPIO\n");
>  
>  		conn->hpd_irq = gpiod_to_irq(conn->hpd_gpio);
> +
> +		conn->enable_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
> +							 GPIOD_OUT_HIGH);

What does it mean to "enable the connector" ? Given that you don't set
the GPIO value at runtime, this seems to be a hack that is probably
better handled with GPIO hogs in the device tree.

> +		if (IS_ERR(conn->enable_gpio))
> +			return dev_err_probe(&pdev->dev, PTR_ERR(conn->enable_gpio),
> +					     "Unable to retrieve enable GPIO\n");
>  	} else {
>  		conn->hpd_irq = -EINVAL;
>  	}

-- 
Regards,

Laurent Pinchart