[PATCH v3 2/7] drm/mgag200: Fail on I2C initialization errors

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Initialization of the I2C adapter was allowed to fail. The mgag200
driver would have continued without DDC support. Had this happened in
practice, it would have led to segmentation faults in the connector
code. Resolve this problem by failing driver initialization on I2C-
related errors.

v2:
	* initialize 'ret' before drm_err() (kernel test robot)

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Reviewed-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
Tested-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
---
 drivers/gpu/drm/mgag200/mgag200_i2c.c  | 13 ++++++++-----
 drivers/gpu/drm/mgag200/mgag200_mode.c |  7 +++++--
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_i2c.c b/drivers/gpu/drm/mgag200/mgag200_i2c.c
index ac8e34eef513..31e2c641a781 100644
--- a/drivers/gpu/drm/mgag200/mgag200_i2c.c
+++ b/drivers/gpu/drm/mgag200/mgag200_i2c.c
@@ -120,7 +120,7 @@ struct mga_i2c_chan *mgag200_i2c_create(struct drm_device *dev)
 
 	i2c = kzalloc(sizeof(struct mga_i2c_chan), GFP_KERNEL);
 	if (!i2c)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	i2c->data = data;
 	i2c->clock = clock;
@@ -142,11 +142,14 @@ struct mga_i2c_chan *mgag200_i2c_create(struct drm_device *dev)
 	i2c->bit.getscl		= mga_gpio_getscl;
 
 	ret = i2c_bit_add_bus(&i2c->adapter);
-	if (ret) {
-		kfree(i2c);
-		i2c = NULL;
-	}
+	if (ret)
+		goto err_kfree;
+
 	return i2c;
+
+err_kfree:
+	kfree(i2c);
+	return ERR_PTR(ret);
 }
 
 void mgag200_i2c_destroy(struct mga_i2c_chan *i2c)
diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 762b9657ae8d..b227891d01ec 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -849,8 +849,11 @@ static int mgag200_vga_connector_init(struct mga_device *mdev)
 	int ret;
 
 	i2c = mgag200_i2c_create(dev);
-	if (!i2c)
-		drm_warn(dev, "failed to add DDC bus\n");
+	if (IS_ERR(i2c)) {
+		ret = PTR_ERR(i2c)
+		drm_err(dev, "failed to add DDC bus: %d\n", ret);
+		return ret;
+	}
 
 	ret = drm_connector_init_with_ddc(dev, connector,
 					  &mga_vga_connector_funcs,
-- 
2.36.1