linux-kernel - Re: [PATCH v17 6/6] drm/bridge: display-connector: add ddc-en gpio support

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Date:   Thu, 7 Apr 2022 10:30:46 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     "H. Nikolaus Schaller" <hns@...delico.com>
Cc:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Paul Boddie <paul@...die.org.uk>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Paul Cercueil <paul@...pouillou.net>,
        Maxime Ripard <maxime@...no.tech>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-mips@...r.kernel.org,
        letux-kernel@...nphoenux.org
Subject: Re: [PATCH v17 6/6] drm/bridge: display-connector: add ddc-en gpio
 support

Hi Nikolaus,

Thank you for the patch.

On Wed, Apr 06, 2022 at 06:26:08PM +0200, H. Nikolaus Schaller wrote:
> "hdmi-connector.yaml" bindings defines an optional property
> "ddc-en-gpios" for a single gpio to enable DDC operation.
> 
> Usually this controls +5V power on the HDMI connector.
> This +5V may also be needed for HPD.
> 
> This was not reflected in code but is needed to make the CI20
> board work.
> 
> Now, the driver activates the ddc gpio after probe and
> deactivates after remove so it is "almost on".
> 
> But only if this driver is loaded (and not e.g. blacklisted
> as module).
> 
> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
>  drivers/gpu/drm/bridge/display-connector.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/display-connector.c b/drivers/gpu/drm/bridge/display-connector.c
> index d24f5b90feabf..e4d52a7e31b71 100644
> --- a/drivers/gpu/drm/bridge/display-connector.c
> +++ b/drivers/gpu/drm/bridge/display-connector.c
> @@ -24,6 +24,7 @@ struct display_connector {
>  	int			hpd_irq;
>  
>  	struct regulator	*dp_pwr;
> +	struct gpio_desc	*ddc_en;
>  };
>  
>  static inline struct display_connector *
> @@ -345,6 +346,17 @@ static int display_connector_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> +	/* enable DDC */
> +	if (type == DRM_MODE_CONNECTOR_HDMIA) {
> +		conn->ddc_en = devm_gpiod_get_optional(&pdev->dev, "ddc-en",
> +						       GPIOD_OUT_HIGH);
> +
> +		if (IS_ERR(conn->ddc_en)) {
> +			dev_err(&pdev->dev, "Couldn't get ddc-en gpio\n");
> +			return PTR_ERR(conn->ddc_en);
> +		}
> +	}
> +
>  	conn->bridge.funcs = &display_connector_bridge_funcs;
>  	conn->bridge.of_node = pdev->dev.of_node;
>  
> @@ -373,6 +385,9 @@ static int display_connector_remove(struct platform_device *pdev)
>  {
>  	struct display_connector *conn = platform_get_drvdata(pdev);
>  
> +	if (conn->ddc_en)
> +		gpiod_set_value(conn->ddc_en, 0);
> +
>  	if (conn->dp_pwr)
>  		regulator_disable(conn->dp_pwr);
>  

-- 
Regards,

Laurent Pinchart