drm/vc4: hdmi: Handle error case of pm_runtime_resume_and_get

The commit 0f525133 ("drm/vc4: hdmi: Make sure the controller is
powered in detect") introduced the necessary power management handling
to avoid register access while controller is powered down.
Unfortunately it just print a warning if pm_runtime_resume_and_get()
fails and proceed anyway.

This could happen during suspend to idle. So we must assume it is unsafe
to access the HDMI register. So bail out properly.

Fixes: 0f525133 ("drm/vc4: hdmi: Make sure the controller is powered in detect")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240821214052.6800-3-wahrenst@gmx.net

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -429,6 +429,7 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
 {
 	struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
 	enum drm_connector_status status = connector_status_disconnected;
+	int ret;
 
 	/*
 	 * NOTE: This function should really take vc4_hdmi->mutex, but
@@ -441,7 +442,12 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
 	 * the lock for now.
 	 */
 
-	WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev));
+	ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev);
+	if (ret) {
+		drm_err_once(connector->dev, "Failed to retain HDMI power domain: %d\n",
+			     ret);
+		return connector_status_unknown;
+	}
 
 	if (vc4_hdmi->hpd_gpio) {
 		if (gpiod_get_value_cansleep(vc4_hdmi->hpd_gpio))