[PATCH 5/5] drm/vc4: kms: Fix IS_ERR() vs NULL check for vc4_kms

[Gaosheng Cui]

The drm_atomic_get_new_private_obj_state() function returns NULL
on error path, drm_atomic_get_old_private_obj_state() function
returns NULL on error path, too, they does not return error pointers.

By the way, vc4_hvs_get_new/old_global_state() should return
ERR_PTR(-EINVAL), otherwise there will be null-ptr-defer issue,
such as follows:

In function vc4_atomic_commit_tail():
  |-- old_hvs_state = vc4_hvs_get_old_global_state(state); <-- return NULL
  |-- if (WARN_ON(IS_ERR(old_hvs_state))) <-- no return
  |-- unsigned long state_rate = max(old_hvs_state->core_clock_rate,
	new_hvs_state->core_clock_rate); <-- null-ptr-defer

Fixes: 9ec03d7f1ed3 ("drm/vc4: kms: Wait on previous FIFO users before a commit")
Signed-off-by: Gaosheng Cui <cuigaosheng1 at huawei.com>
---
 drivers/gpu/drm/vc4/vc4_kms.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_kms.c b/drivers/gpu/drm/vc4/vc4_kms.c
index 5c97642ed66a..8fbeecdf2ec4 100644
--- a/drivers/gpu/drm/vc4/vc4_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_kms.c
@@ -197,8 +197,8 @@ vc4_hvs_get_new_global_state(struct drm_atomic_state *state)
 	struct drm_private_state *priv_state;
 
 	priv_state = drm_atomic_get_new_private_obj_state(state, &vc4->hvs_channels);
-	if (IS_ERR(priv_state))
-		return ERR_CAST(priv_state);
+	if (!priv_state)
+		return ERR_PTR(-EINVAL);
 
 	return to_vc4_hvs_state(priv_state);
 }
@@ -210,8 +210,8 @@ vc4_hvs_get_old_global_state(struct drm_atomic_state *state)
 	struct drm_private_state *priv_state;
 
 	priv_state = drm_atomic_get_old_private_obj_state(state, &vc4->hvs_channels);
-	if (IS_ERR(priv_state))
-		return ERR_CAST(priv_state);
+	if (!priv_state)
+		return ERR_PTR(-EINVAL);
 
 	return to_vc4_hvs_state(priv_state);
 }
-- 
2.25.1