drm/tidss: Drop explicit drm_mode_config_cleanup call

It's right above the drm_dev_put().

This is made possible by a preceeding patch which added a drmm_
cleanup action to drm_mode_config_init(), hence all we need to do to
ensure that drm_mode_config_cleanup() is run on final drm_device
cleanup is check the new error code for _init().

Aside: Another driver with a bit much devm_kzalloc, which should
probably use drmm_kzalloc instead ...

I'm pretty sure this one blows up already under KASAN because it's
using devm_drm_dev_init, and later on devm_kzalloc. Hence the memory
will get freed before the final drm_dev_put (all from the devres
code), but the cleanup in that final drm_dev_put will access the just
freed memory.

Unfortunately fixing this properly needs slightly more work, namely
drmm_ versions for all the drm objects (planes, crtc, ...), so that
the cleanup actually happens before even drmm_kzalloc would release
the underlying memory. Not quite there yet.

v2: Explain why this cleanup is possible (Laurent).

v3: Use drmm_mode_config_init() for more clarity (Sam, Thomas)

Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Jyri Sarha <jsarha@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200323144950.3018436-42-daniel.vetter@ffwll.ch

drivers/gpu/drm/tidss/tidss_drv.c

@@ -103,11 +103,7 @@ static const struct dev_pm_ops tidss_pm_ops = {
 
 static void tidss_release(struct drm_device *ddev)
 {
-	struct tidss_device *tidss = ddev->dev_private;
-
 	drm_kms_helper_poll_fini(ddev);
-
-	tidss_modeset_cleanup(tidss);
 }
 
 DEFINE_DRM_GEM_CMA_FOPS(tidss_fops);

drivers/gpu/drm/tidss/tidss_kms.c

@@ -258,7 +258,9 @@ int tidss_modeset_init(struct tidss_device *tidss)
 
 	dev_dbg(tidss->dev, "%s\n", __func__);
 
-	drm_mode_config_init(ddev);
+	ret = drmm_mode_config_init(ddev);
+	if (ret)
+		return ret;
 
 	ddev->mode_config.min_width = 8;
 	ddev->mode_config.min_height = 8;
@@ -270,11 +272,11 @@ int tidss_modeset_init(struct tidss_device *tidss)
 
 	ret = tidss_dispc_modeset_init(tidss);
 	if (ret)
-		goto err_mode_config_cleanup;
+		return ret;
 
 	ret = drm_vblank_init(ddev, tidss->num_crtcs);
 	if (ret)
-		goto err_mode_config_cleanup;
+		return ret;
 
 	/* Start with vertical blanking interrupt reporting disabled. */
 	for (i = 0; i < tidss->num_crtcs; ++i)
@@ -285,15 +287,4 @@ int tidss_modeset_init(struct tidss_device *tidss)
 	dev_dbg(tidss->dev, "%s done\n", __func__);
 
 	return 0;
-
-err_mode_config_cleanup:
-	drm_mode_config_cleanup(ddev);
-	return ret;
-}
-
-void tidss_modeset_cleanup(struct tidss_device *tidss)
-{
-	struct drm_device *ddev = &tidss->ddev;
-
-	drm_mode_config_cleanup(ddev);
 }

drivers/gpu/drm/tidss/tidss_kms.h

@@ -10,6 +10,5 @@
 struct tidss_device;
 
 int tidss_modeset_init(struct tidss_device *tidss);
-void tidss_modeset_cleanup(struct tidss_device *tidss);
 
 #endif