drm/arc: Switch to devm_drm_dev_alloc

- Need to embedded the drm_device, but for now we keep the usual
  pointer chasing.
- No more devm_kzalloc, which fixes a lifetime issues on driver
  remove.
- No more drm_dev_put, that's done by devm_ now.

Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210112084358.2771527-1-daniel.vetter@ffwll.ch

drivers/gpu/drm/arc/arcpgu.h

@@ -9,6 +9,7 @@
 #define _ARCPGU_H_
 
 struct arcpgu_drm_private {
+	struct drm_device	drm;
 	void __iomem		*regs;
 	struct clk		*clk;
 	struct drm_framebuffer	*fb;

drivers/gpu/drm/arc/arcpgu_drv.c

@@ -42,18 +42,14 @@ static void arcpgu_setup_mode_config(struct drm_device *drm)
 
 DEFINE_DRM_GEM_CMA_FOPS(arcpgu_drm_ops);
 
-static int arcpgu_load(struct drm_device *drm)
+static int arcpgu_load(struct arcpgu_drm_private *arcpgu)
 {
-	struct platform_device *pdev = to_platform_device(drm->dev);
-	struct arcpgu_drm_private *arcpgu;
+	struct platform_device *pdev = to_platform_device(arcpgu->drm.dev);
 	struct device_node *encoder_node = NULL, *endpoint_node = NULL;
+	struct drm_device *drm = &arcpgu->drm;
 	struct resource *res;
 	int ret;
 
-	arcpgu = devm_kzalloc(&pdev->dev, sizeof(*arcpgu), GFP_KERNEL);
-	if (arcpgu == NULL)
-		return -ENOMEM;
-
 	drm->dev_private = arcpgu;
 
 	arcpgu->clk = devm_clk_get(drm->dev, "pxlclk");
@@ -162,30 +158,28 @@ static const struct drm_driver arcpgu_drm_driver = {
 
 static int arcpgu_probe(struct platform_device *pdev)
 {
-	struct drm_device *drm;
+	struct arcpgu_drm_private *arcpgu;
 	int ret;
 
-	drm = drm_dev_alloc(&arcpgu_drm_driver, &pdev->dev);
-	if (IS_ERR(drm))
-		return PTR_ERR(drm);
+	arcpgu = devm_drm_dev_alloc(&pdev->dev, &arcpgu_drm_driver,
+				    struct arcpgu_drm_private, drm);
+	if (IS_ERR(arcpgu))
+		return PTR_ERR(arcpgu);
 
-	ret = arcpgu_load(drm);
+	ret = arcpgu_load(arcpgu);
 	if (ret)
-		goto err_unref;
+		return ret;
 
-	ret = drm_dev_register(drm, 0);
+	ret = drm_dev_register(&arcpgu->drm, 0);
 	if (ret)
 		goto err_unload;
 
-	drm_fbdev_generic_setup(drm, 16);
+	drm_fbdev_generic_setup(&arcpgu->drm, 16);
 
 	return 0;
 
 err_unload:
-	arcpgu_unload(drm);
-
-err_unref:
-	drm_dev_put(drm);
+	arcpgu_unload(&arcpgu->drm);
 
 	return ret;
 }
@@ -196,7 +190,6 @@ static int arcpgu_remove(struct platform_device *pdev)
 
 	drm_dev_unregister(drm);
 	arcpgu_unload(drm);
-	drm_dev_put(drm);
 
 	return 0;
 }