drm/tegra: hdmi - Add connector supply support

Revert commit 18ebc0f4 "drm/tegra: hdmi: Enable VDD earlier for
hotplug/DDC" and instead add a new supply for the +5V pin on the HDMI
connector.

The vdd-supply property refers to the regulator that supplies the
AVDD_HDMI input on Tegra, rather than the +5V HDMI connector pin. This
was never a problem before, because all boards had that pin hooked up to
a regulator that was always on. Starting with Dalmore and continuing
with Venice2, the +5V pin is controllable via a GPIO. For reasons
unknown, the GPIO ended up as the controlling GPIO of the AVDD_HDMI
supply in the Dalmore and Venice2 DTS files. But that's not correct.
Instead, a separate supply must be introduced so that the +5V pin can be
controlled separately from the supplies that feed the HDMI block within
Tegra.

A new hdmi-supply property is introduced that takes the place of the
vdd-supply and vdd-supply is only enabled when HDMI is enabled rather
than all the time.
Signed-off-by: Thierry Reding <treding@nvidia.com>

Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt

@@ -136,6 +136,7 @@ of the following host1x client modules:
   - compatible: "nvidia,tegra<chip>-hdmi"
   - reg: Physical base address and length of the controller's registers.
   - interrupts: The interrupt outputs from the controller.
+  - hdmi-supply: supply for the +5V HDMI connector pin
   - vdd-supply: regulator for supply voltage
   - pll-supply: regulator for PLL
   - clocks: Must contain an entry for each entry in clock-names.

drivers/gpu/drm/tegra/hdmi.c

@@ -42,6 +42,7 @@ struct tegra_hdmi {
 	struct device *dev;
 	bool enabled;
 
+	struct regulator *hdmi;
 	struct regulator *vdd;
 	struct regulator *pll;
 
@@ -710,6 +711,12 @@ static int tegra_output_hdmi_enable(struct tegra_output *output)
 	h_back_porch = mode->htotal - mode->hsync_end;
 	h_front_porch = mode->hsync_start - mode->hdisplay;
 
+	err = regulator_enable(hdmi->vdd);
+	if (err < 0) {
+		dev_err(hdmi->dev, "failed to enable VDD regulator: %d\n", err);
+		return err;
+	}
+
 	err = regulator_enable(hdmi->pll);
 	if (err < 0) {
 		dev_err(hdmi->dev, "failed to enable PLL regulator: %d\n", err);
@@ -950,6 +957,7 @@ static int tegra_output_hdmi_disable(struct tegra_output *output)
 	reset_control_assert(hdmi->rst);
 	clk_disable(hdmi->clk);
 	regulator_disable(hdmi->pll);
+	regulator_disable(hdmi->vdd);
 
 	hdmi->enabled = false;
 
@@ -1256,13 +1264,6 @@ static int tegra_hdmi_init(struct host1x_client *client)
 	struct tegra_hdmi *hdmi = host1x_client_to_hdmi(client);
 	int err;
 
-	err = regulator_enable(hdmi->vdd);
-	if (err < 0) {
-		dev_err(client->dev, "failed to enable VDD regulator: %d\n",
-			err);
-		return err;
-	}
-
 	hdmi->output.type = TEGRA_OUTPUT_HDMI;
 	hdmi->output.dev = client->dev;
 	hdmi->output.ops = &hdmi_ops;
@@ -1279,6 +1280,13 @@ static int tegra_hdmi_init(struct host1x_client *client)
 			dev_err(client->dev, "debugfs setup failed: %d\n", err);
 	}
 
+	err = regulator_enable(hdmi->hdmi);
+	if (err < 0) {
+		dev_err(client->dev, "failed to enable HDMI regulator: %d\n",
+			err);
+		return err;
+	}
+
 	return 0;
 }
 
@@ -1287,6 +1295,8 @@ static int tegra_hdmi_exit(struct host1x_client *client)
 	struct tegra_hdmi *hdmi = host1x_client_to_hdmi(client);
 	int err;
 
+	regulator_disable(hdmi->hdmi);
+
 	if (IS_ENABLED(CONFIG_DEBUG_FS)) {
 		err = tegra_hdmi_debugfs_exit(hdmi);
 		if (err < 0)
@@ -1306,8 +1316,6 @@ static int tegra_hdmi_exit(struct host1x_client *client)
 		return err;
 	}
 
-	regulator_disable(hdmi->vdd);
-
 	return 0;
 }
 
@@ -1399,6 +1407,12 @@ static int tegra_hdmi_probe(struct platform_device *pdev)
 		return err;
 	}
 
+	hdmi->hdmi = devm_regulator_get(&pdev->dev, "hdmi");
+	if (IS_ERR(hdmi->hdmi)) {
+		dev_err(&pdev->dev, "failed to get HDMI regulator\n");
+		return PTR_ERR(hdmi->hdmi);
+	}
+
 	hdmi->vdd = devm_regulator_get(&pdev->dev, "vdd");
 	if (IS_ERR(hdmi->vdd)) {
 		dev_err(&pdev->dev, "failed to get VDD regulator\n");