Hi
Am 30.05.26 um 15:59 schrieb Maxime Ripard:
Commit 47b5ac7daa46 ("drm/atomic: Add new atomic_create_state callback
to drm_private_obj") introduced a new pattern for allocating drm object
states: atomic_create_state, a dedicated hook that allocates and
initializes a pristine state without any side effect.
The bridge atomic_reset callback is already fallible and in practice
only allocates and initializes state without touching hardware.
However, the reset name does not make this contract clear: callers
and implementers cannot tell from the name alone whether the hardware
will be affected or when the hook is safe to call.
Add an atomic_create_state callback to drm_bridge_funcs to make the
contract explicit: allocate a pristine state, initialize it, no side
effects. The core calls it when available, falling back to
atomic_reset otherwise.
Signed-off-by: Maxime Ripard <[email protected]>
---
drivers/gpu/drm/drm_bridge.c | 8 ++++++--
include/drm/drm_bridge.h | 33 +++++++++++----------------------
2 files changed, 17 insertions(+), 24 deletions(-)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 687b36eea0c7..ef06c1aa509a 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -498,11 +498,14 @@ static struct drm_private_state *
drm_bridge_atomic_create_priv_state(struct drm_private_obj *obj)
{
struct drm_bridge *bridge = drm_priv_to_bridge(obj);
struct drm_bridge_state *state;
- state = bridge->funcs->atomic_reset(bridge);
+ if (bridge->funcs->atomic_create_state)
+ state = bridge->funcs->atomic_create_state(bridge);
+ else
+ state = bridge->funcs->atomic_reset(bridge);
if (IS_ERR(state))
return ERR_CAST(state);
return &state->base;
}
@@ -513,11 +516,12 @@ static const struct drm_private_state_funcs
drm_bridge_priv_state_funcs = {
.atomic_destroy_state = drm_bridge_atomic_destroy_priv_state,
};
static bool drm_bridge_is_atomic(struct drm_bridge *bridge)
{
- return bridge->funcs->atomic_reset != NULL;
+ return (bridge->funcs->atomic_create_state ||
+ bridge->funcs->atomic_reset);
}
/**
* drm_bridge_attach - attach the bridge to an encoder's chain
*
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 4ba3a5deef9a..a6c07d339afa 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -502,35 +502,24 @@ struct drm_bridge_funcs {
struct drm_bridge_state *bridge_state,
struct drm_crtc_state *crtc_state,
struct drm_connector_state *conn_state);
/**
- * @atomic_reset:
+ * @atomic_create_state:
*
- * Reset the bridge to a predefined state (or retrieve its current
- * state) and return a &drm_bridge_state object matching this state.
- * This function is called at attach time.
- *
- * The atomic_reset hook is mandatory if the bridge implements any of
- * the atomic hooks, and should be left unassigned otherwise. For
- * bridges that don't subclass &drm_bridge_state, the
- * drm_atomic_helper_bridge_reset() helper function shall be used to
- * implement this hook.
- *
- * Note that the atomic_reset() semantics is not exactly matching the
- * reset() semantics found on other components (connector, plane, ...).
- *
- * 1. The reset operation happens when the bridge is attached, not when
- * drm_mode_config_reset() is called
- * 2. It's meant to be used exclusively on bridges that have been
- * converted to the ATOMIC API
+ * Allocate a pristine, initialized, state for the bridge
+ * object and return it. This callback must have no side
+ * effects: in particular, the returned state must not be
+ * assigned to the object's state pointer and it must not affect
+ * the hardware state.
*
* RETURNS:
- * A valid drm_bridge_state object in case of success, an ERR_PTR()
- * giving the reason of the failure otherwise.
+ *
+ * A new, pristine, bridge state instance or an error pointer
+ * on failure.
*/
- struct drm_bridge_state *(*atomic_reset)(struct drm_bridge *bridge);
This needs to remain for now, right?
Best regards
Thomas
+ struct drm_bridge_state *(*atomic_create_state)(struct drm_bridge
*bridge);
/**
* @detect:
*
* Check if anything is attached to the bridge output.
@@ -1369,11 +1358,11 @@ drm_bridge_get_current_state(struct drm_bridge *bridge)
/*
* Only atomic bridges will have bridge->base initialized by
* drm_atomic_private_obj_init(), so we need to make sure we're
* working with one before we try to use the lock.
*/
- if (!bridge->funcs || !bridge->funcs->atomic_reset)
+ if (!bridge->funcs || !bridge->funcs->atomic_create_state)
return NULL;
drm_modeset_lock_assert_held(&bridge->base.lock);
if (!bridge->base.state)
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)
