Re: [PATCH v12 7/9] drm/bridge: display-connector: add ddc-en gpio support

[Paul Cercueil <paul@crapouillou.net>]

Hi Nikolaus,

Le lun., janv. 31 2022 at 13:26:53 +0100, H. Nikolaus Schaller 
<hns@goldelico.com> a écrit :
> "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.
> 
> 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@goldelico.com>
> ---
>  drivers/gpu/drm/bridge/display-connector.c | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/display-connector.c 
> b/drivers/gpu/drm/bridge/display-connector.c
> index d24f5b90feabf..555395e301096 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 +346,19 @@ 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);
> +		}
> +
> +		gpiod_set_value(conn->ddc_en, 1);

You already requested the gpio with the GPIOD_OUT_HIGH flag, so this 
can be removed.


> +	}
> +
>  	conn->bridge.funcs = &display_connector_bridge_funcs;
>  	conn->bridge.of_node = pdev->dev.of_node;
> 
> @@ -373,6 +387,9 @@ 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);

Note that gpiod_set_value() already does the null-check internally. I 
actually do prefer your solution, so this is fine with me, but 
maintainers may have a different opinion.

Cheers,
-Paul

> +
>  	if (conn->dp_pwr)
>  		regulator_disable(conn->dp_pwr);
> 
> --
> 2.33.0
>