From: Rob Clark <rob@xxxxxx>
This indicates to userspace that the property is something that can
be set dynamically without requiring a "test" step to check if the
hw is capable. This allows a userspace compositor, such as weston,
to avoid an extra ioctl to check whether it needs to fall-back to
GPU to composite some surface prior to submission of GPU render
commands.
---
include/drm/drm_mode.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/include/drm/drm_mode.h b/include/drm/drm_mode.h
index dff792f..e03ece6 100644
--- a/include/drm/drm_mode.h
+++ b/include/drm/drm_mode.h
@@ -232,6 +232,15 @@ struct drm_mode_get_connector {
#define DRM_MODE_PROP_BLOB (1<<4)
#define DRM_MODE_PROP_BITMASK (1<<5) /* bitmask of enumerated types */
#define DRM_MODE_PROP_OBJECT (1<<6) /* drm mode object */
+/* Properties that are not dynamic cannot safely be changed without a
+ * atomic-modeset / atomic-pageflip test step. But if userspace is
+ * only changing dynamic properties, it is guaranteed that the change
+ * will not exceed hw limits, so no test step is required.
+ *
+ * Note that fb_id properties are a bit ambiguous.. they of course can
+ * be changed dynamically, assuming the pixel format does not change.
+ */
+#define DRM_MODE_PROP_DYNAMIC (1<<24)
struct drm_mode_property_enum {
__u64 value;
--
1.7.9.5
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