drm/nouveau: Convert to atomic_create_state

The plane reset implementation creates a custom state
subclass, but only initializes a pristine state without resetting any
hardware. This is equivalent to what atomic_create_state expects.
Convert to it.

The conversion was done using the following Coccinelle semantic patch:

@@
identifier funcs;
symbol drm_atomic_helper_plane_reset;
symbol drm_atomic_helper_plane_create_state;
@@

struct drm_plane_funcs funcs = {
  ...,
- .reset = drm_atomic_helper_plane_reset,
+ .atomic_create_state = drm_atomic_helper_plane_create_state,
  ...,
};

@match_struct_reset@
identifier funcs, reset_func;
@@
struct drm_plane_funcs funcs = {
    ...,
    .reset = reset_func,
    ...,
};

@reset_uses_helpers depends on match_struct_reset@
identifier match_struct_reset.reset_func;
@@

 void reset_func(...)
 {
 	<+...
(
 	__drm_atomic_helper_plane_reset(...);
|
	__drm_gem_reset_shadow_plane(...);
)
 	...+>
 }

@match_struct_destroy@
identifier funcs, destroy_func;
@@
struct drm_plane_funcs funcs = {
    ...,
    .atomic_destroy_state = destroy_func,
    ...,
};

@script:python renamed_func@
old_name << match_struct_reset.reset_func;
new_name;
@@
if old_name.endswith("_reset"):
    coccinelle.new_name = old_name.replace("_reset", "_create_state")
else:
    coccinelle.new_name = old_name

@update_struct depends on match_struct_reset && reset_uses_helpers@
identifier match_struct_reset.funcs, match_struct_reset.reset_func;
identifier renamed_func.new_name;
@@
struct drm_plane_funcs funcs = {
    ...,
-   .reset = reset_func,
+   .atomic_create_state = new_name,
    ...,
};

@drop_destroy depends on update_struct && match_struct_destroy@
identifier match_struct_reset.reset_func;
identifier match_struct_destroy.destroy_func;
identifier container_func;
identifier P;
symbol drm_atomic_helper_plane_destroy_state;
symbol __drm_atomic_helper_plane_destroy_state;
@@

 void reset_func(struct drm_plane *P)
 {
 	...
(
-	if (P->state) {
- 		<+...
(
-		drm_atomic_helper_plane_destroy_state(P, P->state);
|
-		__drm_atomic_helper_plane_destroy_state(P->state);
|
-		P->funcs->atomic_destroy_state(P, P->state);
|
-		destroy_func(P, P->state);
)
- 		...+>
- 	}
|
-	drm_WARN_ON_ONCE(P->dev, P->state);
|
-	WARN_ON(P->state);
)
 	...
(
-	kfree(P->state);
|
-	kfree(container_func(P->state));
|
 	// kfree is optional
)
(
-	P->state = NULL;
|
 	// plane->state clearing is optional
)
 	...
 }

@drop_destroy_mtk depends on update_struct@
identifier P;
symbol __drm_atomic_helper_plane_destroy_state;
symbol to_mtk_plane_state;
@@

 void mtk_plane_reset(struct drm_plane *P)
 {
 	...
-	if (P->state) {
-		__drm_atomic_helper_plane_destroy_state(P->state);
-		...
-	} else {
 		...
-	}
 	...
 }

@transform_nv50_wndw depends on update_struct@
identifier S;
@@

 void nv50_wndw_reset(...)
 {
 	...
-	if (WARN_ON(!(S = kzalloc_obj(*S))))
+	S = kzalloc_obj(*S);
+	if (WARN_ON(!S))
 		return;
 	...
 }

@transform_kzalloc depends on update_struct@
identifier match_struct_reset.reset_func;
identifier P, S;
statement ST;
statement list STL;
@@

 void reset_func(struct drm_plane *P)
 {
 	<...
 	S = kzalloc_obj(*S);
(
-	if (S)
-	{
-		STL
-	}
+	if (!S) return;
+
+	STL
|
-	if (S) ST
+	if (!S) return;
+
+	ST
)
	...>
 }

@transform_body depends on update_struct@
identifier match_struct_reset.reset_func;
identifier renamed_func.new_name;
identifier S, P;
expression PS;
@@
- void reset_func(struct drm_plane *P)
+ struct drm_plane_state *new_name(struct drm_plane *P)
{
	...
 	S = kzalloc_obj(*S);
	...
(
 	if (!S) {
		...
-		return;
+		return ERR_PTR(-ENOMEM);
 	}
|
 	if (WARN_ON(!S)) {
		...
-		return;
+		return ERR_PTR(-ENOMEM);
 	}
|
 	if (S == NULL) {
 		...
-		return;
+		return ERR_PTR(-ENOMEM);
 	}
)
	...
(
-	__drm_atomic_helper_plane_reset(P, PS);
+	__drm_atomic_helper_plane_state_init(PS, P);
|
-	__drm_gem_reset_shadow_plane(P, PS);
+	__drm_gem_shadow_plane_state_init(P, PS);
)
	...
}

@update_early_return depends on update_struct@
identifier match_struct_reset.reset_func;
identifier renamed_func.new_name;
identifier P;
expression PS;
@@
 struct drm_plane_state *new_name(struct drm_plane *P)
{
	<+...
-	return;
+	return ERR_PTR(-EINVAL);
	...+>
}

@update_return_plane depends on update_struct@
identifier match_struct_reset.reset_func;
identifier renamed_func.new_name;
identifier P;
expression PS;
@@
 struct drm_plane_state *new_name(struct drm_plane *P)
{
	...
 	__drm_atomic_helper_plane_state_init(PS, P);
	...
+
+	return PS;
}

@update_return_shadow depends on update_struct@
identifier renamed_func.new_name;
identifier P;
expression PS;
@@
 struct drm_plane_state *new_name(struct drm_plane *P)
{
	...
 	__drm_gem_shadow_plane_state_init(P, PS);
	...
+
+	return &PS->base;
}

Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20260908-drm-no-more-plane-reset-v4-33-a31b3fcfc989@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>

1 files changed, 7 insertions, 8 deletions

diff --git a/drivers/gpu/drm/nouveau/dispnv50/wndw.c b/drivers/gpu/drm/nouveau/dispnv50/wndw.c
index 15a322422f4e..378095138d12 100644
--- a/drivers/gpu/drm/nouveau/dispnv50/wndw.c
+++ b/drivers/gpu/drm/nouveau/dispnv50/wndw.c
@@ -752,18 +752,17 @@ nv50_wndw_zpos_default(struct drm_plane *plane)
 	       (plane->type == DRM_PLANE_TYPE_OVERLAY) ? 1 : 255;
 }
 
-static void
-nv50_wndw_reset(struct drm_plane *plane)
+static struct drm_plane_state *nv50_wndw_create_state(struct drm_plane *plane)
 {
 	struct nv50_wndw_atom *asyw;
 
-	if (WARN_ON(!(asyw = kzalloc_obj(*asyw))))
-		return;
+	asyw = kzalloc_obj(*asyw);
+	if (WARN_ON(!asyw))
+		return ERR_PTR(-ENOMEM);
 
-	if (plane->state)
-		plane->funcs->atomic_destroy_state(plane, plane->state);
+	__drm_atomic_helper_plane_state_init(&asyw->state, plane);
 
-	__drm_atomic_helper_plane_reset(plane, &asyw->state);
+	return &asyw->state;
 }
 
 static void
@@ -837,7 +836,7 @@ nv50_wndw = {
 	.update_plane = drm_atomic_helper_update_plane,
 	.disable_plane = drm_atomic_helper_disable_plane,
 	.destroy = nv50_wndw_destroy,
-	.reset = nv50_wndw_reset,
+	.atomic_create_state = nv50_wndw_create_state,
 	.atomic_duplicate_state = nv50_wndw_atomic_duplicate_state,
 	.atomic_destroy_state = nv50_wndw_atomic_destroy_state,
 	.format_mod_supported = nv50_plane_format_mod_supported,