[PATCH 3/3] ipuv3-ldb: add remove action for devres data

[Michael Grzeschik <m.grzeschik@pengutronix.de>]

The destroy function in drm_mode_config_cleanup will remove the objects
in ipu-drm-core by calling its destroy functions if the bind function
fails. The drm_encoder is also part of the devres allocated ipu_ldb
object. The ipu_ldb object will already be cleaned up if the bind for
the crtc fails. This leads drm_encoder_cleanup try to clean already freed
memory.

We fix this issue by adding the devres action ipu_ldb_remove_head which
will remove its head from the objects in ipu-drm-core which then never
calls its destroy function anymore.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
---
 drivers/gpu/drm/imx/imx-ldb.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/imx/imx-ldb.c b/drivers/gpu/drm/imx/imx-ldb.c
index a11f8758da70e..0a224036cc68d 100644
--- a/drivers/gpu/drm/imx/imx-ldb.c
+++ b/drivers/gpu/drm/imx/imx-ldb.c
@@ -581,6 +581,21 @@ static int imx_ldb_panel_ddc(struct device *dev,
 	return 0;
 }
 
+static void ipu_ldb_remove_head(void *data)
+{
+	struct imx_ldb *imx_ldb = data;
+	struct imx_ldb_channel *imx_ldb_ch;
+	struct drm_encoder *encoder;
+
+	imx_ldb_ch = &imx_ldb->channel[0];
+	encoder = &imx_ldb_ch->encoder;
+	list_del_init(&encoder->head);
+
+	imx_ldb_ch = &imx_ldb->channel[1];
+	encoder = &imx_ldb_ch->encoder;
+	list_del_init(&encoder->head);
+}
+
 static void ipu_ldb_init_encoder_head(struct imx_ldb *imx_ldb)
 {
 	struct imx_ldb_channel *imx_ldb_ch;
@@ -613,6 +628,10 @@ static int imx_ldb_bind(struct device *dev, struct device *master, void *data)
 
 	ipu_ldb_init_encoder_head(imx_ldb);
 
+	ret = devm_add_action(dev, ipu_ldb_remove_head, imx_ldb);
+	if (ret)
+		return ret;
+
 	imx_ldb->regmap = syscon_regmap_lookup_by_phandle(np, "gpr");
 	if (IS_ERR(imx_ldb->regmap)) {
 		dev_err(dev, "failed to get parent regmap\n");
-- 
2.20.1