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

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Message-Id: <77a7a1daaf381e1651be38adb62f9af9dd6c8fc5.1643632014.git.hns@goldelico.com>
Date:   Mon, 31 Jan 2022 13:26:53 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Paul Cercueil <paul@...pouillou.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "H. Nikolaus Schaller" <hns@...delico.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Kees Cook <keescook@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Harry Wentland <harry.wentland@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        Maxime Ripard <maxime@...no.tech>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Paul Boddie <paul@...die.org.uk>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
Cc:     devicetree@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org, letux-kernel@...nphoenux.org,
        Jonas Karlman <jonas@...boo.se>,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH v12 7/9] 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.

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 | 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