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

[H. Nikolaus Schaller]

"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 at 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);
+	}
+
 	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);
+
 	if (conn->dp_pwr)
 		regulator_disable(conn->dp_pwr);
 
-- 
2.33.0