The atomic_check function is useful for implementing properties, but
it can be used for other connector modeset related checks as well.
Similar to plane check functions, on a modeset atomic_check() is always
called.
Changes since v1:
- Make sure atomic_check() is called on any modeset.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/drm_atomic_helper.c | 44 +++++++++++++++++++++++++++++---
include/drm/drm_modeset_helper_vtables.h | 34 ++++++++++++++++++++++++
2 files changed, 74 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 543ac330a1ae..83567c4091b8 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -459,10 +459,20 @@ mode_fixup(struct drm_atomic_state *state)
*
* Check the state object to see if the requested state is physically possible.
* This does all the crtc and connector related computations for an atomic
- * update and adds any additional connectors needed for full modesets and calls
- * down into &drm_crtc_helper_funcs.mode_fixup and
- * &drm_encoder_helper_funcs.mode_fixup or
- * &drm_encoder_helper_funcs.atomic_check functions of the driver backend.
+ * update and adds any additional connectors needed for full modesets. It calls
+ * the various per-object callbacks in the follow order:
+ *
+ * 1. &drm_connector_helper_funcs.atomic_best_encoder for determining the new encoder.
+ * 2. &drm_connector_helper_funcs.atomic_check to validate the connector state.
+ * 3. If it's determined a modeset is needed then all connectors on the affected crtc
+ * crtc are added and &drm_connector_helper_funcs.atomic_check is run on them.
+ * 4. &drm_bridge_funcs.mode_fixup is called on all encoder bridges.
+ * 5. &drm_encoder_helper_funcs.atomic_check is called to validate any encoder state.
+ * This function is only called when the encoder will be part of a configured crtc,
+ * it must not be used for implementing connector property validation.
+ * If this function is NULL, &drm_atomic_encoder_helper_funcs.mode_fixup is called
+ * instead.
+ * 6. &drm_crtc_helper_funcs.mode_fixup is called last, to fix up the mode with crtc constraints.
*
* &drm_crtc_state.mode_changed is set when the input mode is changed.
* &drm_crtc_state.connectors_changed is set when a connector is added or
@@ -492,6 +502,7 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
struct drm_connector *connector;
struct drm_connector_state *old_connector_state, *new_connector_state;
int i, ret;
+ unsigned connectors_mask = 0;
for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
bool has_connectors =
@@ -538,6 +549,8 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
return ret;
for_each_oldnew_connector_in_state(state, connector, old_connector_state, new_connector_state, i) {
+ const struct drm_connector_helper_funcs *funcs = connector->helper_private;
+
/*
* This only sets crtc->connectors_changed for routing changes,
* drivers must set crtc->connectors_changed themselves when
@@ -555,6 +568,13 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
new_connector_state->link_status)
new_crtc_state->connectors_changed = true;
}
+
+ if (funcs->atomic_check)
+ ret = funcs->atomic_check(connector, new_connector_state);
+ if (ret)
+ return ret;
+
+ connectors_mask += BIT(i);
}
/*
@@ -581,6 +601,22 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
return ret;
}
+ /*
+ * Iterate over all connectors again, to make sure atomic_check()
+ * has been called on them when a modeset is forced.
+ */
+ for_each_oldnew_connector_in_state(state, connector, old_connector_state, new_connector_state, i) {
+ const struct drm_connector_helper_funcs *funcs = connector->helper_private;
+
+ if (connectors_mask & BIT(i))
+ continue;
+
+ if (funcs->atomic_check)
+ ret = funcs->atomic_check(connector, new_connector_state);
+ if (ret)
+ return ret;
+ }
+
return mode_fixup(state);
}
EXPORT_SYMBOL(drm_atomic_helper_check_modeset);
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index 7847babd893c..c01c328f6cc8 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -872,6 +872,40 @@ struct drm_connector_helper_funcs {
*/
struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
struct drm_connector_state *connector_state);
+
+ /**
+ * @atomic_check:
+ *
+ * This hook is used to validate connector state. This function is
+ * called from &drm_atomic_helper_check_modeset, and is called when
+ * a connector property is set, or a modeset on the crtc is forced.
+ *
+ * Because &drm_atomic_helper_check_modeset may be called multiple times,
+ * this function should handle being called multiple times as well.
+ *
+ * This function is also allowed to inspect any other object's state and
+ * can add more state objects to the atomic commit if needed. Care must
+ * be taken though to ensure that state check and compute functions for
+ * these added states are all called, and derived state in other objects
+ * all updated. Again the recommendation is to just call check helpers
+ * until a maximal configuration is reached.
+ *
+ * NOTE:
+ *
+ * This function is called in the check phase of an atomic update. The
+ * driver is not allowed to change anything outside of the free-standing
+ * state objects passed-in or assembled in the overall &drm_atomic_state
+ * update tracking structure.
+ *
+ * RETURNS:
+ *
+ * 0 on success, -EINVAL if the state or the transition can't be
+ * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
+ * attempt to obtain another state object ran into a &drm_modeset_lock
+ * deadlock.
+ */
+ int (*atomic_check)(struct drm_connector *connector,
+ struct drm_connector_state *state);
};
/**
--
2.7.4
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