drm/i915: Initialize fbdev DRM client with callback functions

Initialize i915's fbdev client by giving an instance of struct
drm_client_funcs to drm_client_init(). Also clean up with
drm_client_release().

Doing this in i915 prevents fbdev helpers from initializing and
releasing the client internally (see drm_fb_helper_init()). No
functional change yet; the client callbacks will be filled later.

v6:
- rename client to "intel-fbdev" (Jouni)

v2:
- call drm_fb_helper_unprepare() in error handling (Jani)
- fix typo in commit message (Sam)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Acked-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240409081029.17843-4-tzimmermann@suse.deSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/display/intel_fbdev.c

@@ -291,6 +291,7 @@ static void intel_fbdev_destroy(struct intel_fbdev *ifbdev)
 	if (ifbdev->fb)
 		drm_framebuffer_remove(&ifbdev->fb->base);
 
+	drm_client_release(&ifbdev->helper.client);
 	drm_fb_helper_unprepare(&ifbdev->helper);
 	kfree(ifbdev);
 }
@@ -584,6 +585,30 @@ void intel_fbdev_restore_mode(struct drm_i915_private *dev_priv)
 		intel_fbdev_invalidate(ifbdev);
 }
 
+/*
+ * Fbdev client and struct drm_client_funcs
+ */
+
+static void intel_fbdev_client_unregister(struct drm_client_dev *client)
+{ }
+
+static int intel_fbdev_client_restore(struct drm_client_dev *client)
+{
+	return 0;
+}
+
+static int intel_fbdev_client_hotplug(struct drm_client_dev *client)
+{
+	return 0;
+}
+
+static const struct drm_client_funcs intel_fbdev_client_funcs = {
+	.owner		= THIS_MODULE,
+	.unregister	= intel_fbdev_client_unregister,
+	.restore	= intel_fbdev_client_restore,
+	.hotplug	= intel_fbdev_client_hotplug,
+};
+
 int intel_fbdev_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
@@ -605,16 +630,26 @@ int intel_fbdev_init(struct drm_device *dev)
 	else
 		ifbdev->preferred_bpp = ifbdev->helper.preferred_bpp;
 
+	ret = drm_client_init(dev, &ifbdev->helper.client, "intel-fbdev",
+			      &intel_fbdev_client_funcs);
+	if (ret)
+		goto err_drm_fb_helper_unprepare;
+
 	ret = drm_fb_helper_init(dev, &ifbdev->helper);
-	if (ret) {
-		kfree(ifbdev);
-		return ret;
-	}
+	if (ret)
+		goto err_drm_client_release;
 
 	dev_priv->display.fbdev.fbdev = ifbdev;
 	INIT_WORK(&dev_priv->display.fbdev.suspend_work, intel_fbdev_suspend_worker);
 
 	return 0;
+
+err_drm_client_release:
+	drm_client_release(&ifbdev->helper.client);
+err_drm_fb_helper_unprepare:
+	drm_fb_helper_unprepare(&ifbdev->helper);
+	kfree(ifbdev);
+	return ret;
 }
 
 static void intel_fbdev_initial_config(void *data, async_cookie_t cookie)