diff options
Diffstat (limited to 'include/uapi/drm/i915_drm.h')
| -rw-r--r-- | include/uapi/drm/i915_drm.h | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h index 1a60642c1d61..aa2d4c73a97d 100644 --- a/include/uapi/drm/i915_drm.h +++ b/include/uapi/drm/i915_drm.h @@ -1127,32 +1127,34 @@ struct drm_i915_gem_busy { * as busy may become idle before the ioctl is completed. * * Furthermore, if the object is busy, which engine is busy is only - * provided as a guide. There are race conditions which prevent the - * report of which engines are busy from being always accurate. - * However, the converse is not true. If the object is idle, the - * result of the ioctl, that all engines are idle, is accurate. + * provided as a guide and only indirectly by reporting its class + * (there may be more than one engine in each class). There are race + * conditions which prevent the report of which engines are busy from + * being always accurate. However, the converse is not true. If the + * object is idle, the result of the ioctl, that all engines are idle, + * is accurate. * * The returned dword is split into two fields to indicate both - * the engines on which the object is being read, and the - * engine on which it is currently being written (if any). + * the engine classess on which the object is being read, and the + * engine class on which it is currently being written (if any). * * The low word (bits 0:15) indicate if the object is being written * to by any engine (there can only be one, as the GEM implicit * synchronisation rules force writes to be serialised). Only the - * engine for the last write is reported. + * engine class (offset by 1, I915_ENGINE_CLASS_RENDER is reported as + * 1 not 0 etc) for the last write is reported. * - * The high word (bits 16:31) are a bitmask of which engines are - * currently reading from the object. Multiple engines may be + * The high word (bits 16:31) are a bitmask of which engines classes + * are currently reading from the object. Multiple engines may be * reading from the object simultaneously. * - * The value of each engine is the same as specified in the - * EXECBUFFER2 ioctl, i.e. I915_EXEC_RENDER, I915_EXEC_BSD etc. - * Note I915_EXEC_DEFAULT is a symbolic value and is mapped to - * the I915_EXEC_RENDER engine for execution, and so it is never + * The value of each engine class is the same as specified in the + * I915_CONTEXT_SET_ENGINES parameter and via perf, i.e. + * I915_ENGINE_CLASS_RENDER, I915_ENGINE_CLASS_COPY, etc. * reported as active itself. Some hardware may have parallel * execution engines, e.g. multiple media engines, which are - * mapped to the same identifier in the EXECBUFFER2 ioctl and - * so are not separately reported for busyness. + * mapped to the same class identifier and so are not separately + * reported for busyness. * * Caveat emptor: * Only the boolean result of this query is reliable; that is whether |