From: Rob Clark robdclark@chromium.org
This will allow userspace to control the scheduling policy and priority. In particular if the userspace half of the display pipeline is SCHED_FIFO then it will want to use the same scheduling policy and an appropriate priority to ensure that it is not preempting commit_work.
Signed-off-by: Rob Clark robdclark@chromium.org --- drivers/gpu/drm/drm_crtc.c | 3 +++ drivers/gpu/drm/drm_mode_config.c | 14 ++++++++++++++ drivers/gpu/drm/drm_mode_object.c | 4 ++++ include/drm/drm_mode_config.h | 9 +++++++++ include/drm/drm_property.h | 9 +++++++++ 5 files changed, 39 insertions(+)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 4f7c0bfce0a3..1828853542dc 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -334,6 +334,9 @@ int drm_crtc_init_with_planes(struct drm_device *dev, struct drm_crtc *crtc, crtc->worker = NULL; return ret; } + + drm_object_attach_property(&crtc->base, + config->kwork_tid_property, 0); }
return 0; diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c index f1affc1bb679..b11a1fc8ed0d 100644 --- a/drivers/gpu/drm/drm_mode_config.c +++ b/drivers/gpu/drm/drm_mode_config.c @@ -215,6 +215,13 @@ static const struct drm_prop_enum_list drm_plane_type_enum_list[] = { { DRM_PLANE_TYPE_CURSOR, "Cursor" }, };
+static int get_kwork_tid(struct drm_mode_object *obj, uint64_t *val) +{ + struct drm_crtc *crtc = obj_to_crtc(obj); + *val = task_pid_vnr(crtc->worker->task); + return 0; +} + static int drm_mode_create_standard_properties(struct drm_device *dev) { struct drm_property *prop; @@ -371,6 +378,13 @@ static int drm_mode_create_standard_properties(struct drm_device *dev) return -ENOMEM; dev->mode_config.modifiers_property = prop;
+ prop = drm_property_create_range(dev, DRM_MODE_PROP_ATOMIC, + "KWORK_TID", 0, UINT_MAX); + if (!prop) + return -ENOMEM; + prop->get_value = get_kwork_tid; + dev->mode_config.kwork_tid_property = prop; + return 0; }
diff --git a/drivers/gpu/drm/drm_mode_object.c b/drivers/gpu/drm/drm_mode_object.c index db05f386a709..1a4df65baf0f 100644 --- a/drivers/gpu/drm/drm_mode_object.c +++ b/drivers/gpu/drm/drm_mode_object.c @@ -285,6 +285,7 @@ int drm_object_property_set_value(struct drm_mode_object *obj,
WARN_ON(drm_drv_uses_atomic_modeset(property->dev) && !(property->flags & DRM_MODE_PROP_IMMUTABLE)); + WARN_ON(property->get_value);
for (i = 0; i < obj->properties->count; i++) { if (obj->properties->properties[i] == property) { @@ -303,6 +304,9 @@ static int __drm_object_property_get_value(struct drm_mode_object *obj, { int i;
+ if (property->get_value) + return property->get_value(obj, val); + /* read-only properties bypass atomic mechanism and still store * their value in obj->properties->values[].. mostly to avoid * having to deal w/ EDID and similar props in atomic paths: diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h index c2d3d71d133c..7244df926a6d 100644 --- a/include/drm/drm_mode_config.h +++ b/include/drm/drm_mode_config.h @@ -926,6 +926,15 @@ struct drm_mode_config { */ struct drm_property *modifiers_property;
+ /** + * @kwork_tid_property: CRTC property to expose the task-id of the per- + * CRTC kthread-worker, used for non-block atomic commit. This is exposed + * to userspace, to allow userspace to control the scheduling policy and + * priority, as this is a decision that depends on how userspace structures + * it's rendering pipeline. + */ + struct drm_property *kwork_tid_property; + /* cursor size */ uint32_t cursor_width, cursor_height;
diff --git a/include/drm/drm_property.h b/include/drm/drm_property.h index 4a0a80d658c7..6843be6aa3ec 100644 --- a/include/drm/drm_property.h +++ b/include/drm/drm_property.h @@ -188,6 +188,15 @@ struct drm_property { * enum and bitmask values. */ struct list_head enum_list; + + /** + * @get_value: accessor to get current value for "virtual" properties + * + * For properties with dynamic values, where it is for whatever reason + * not feasible to keep updated with drm_object_property_set_value(), + * this callback can be used to retrieve the current value on demand. + */ + int (*get_value)(struct drm_mode_object *obj, uint64_t *val); };
/**