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

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Date:   Wed,  6 Apr 2022 18:26:08 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Paul Boddie <paul@...die.org.uk>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        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>,
        "H. Nikolaus Schaller" <hns@...delico.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
Cc:     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: [PATCH v17 6/6] drm/bridge: display-connector: add ddc-en gpio support

"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>
---
 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);
 
-- 
2.33.0