DRM全解析 —— CRTC详解（4）

接前一篇文章：DRM全解析 —— CRTC详解（3）

本文继续对DRM中CRTC的核心结构struct drm_crtc的成员进行释义。

3. drm_crtc结构释义

（21）struct drm_object_properties properties

    /** @properties: property tracking for this CRTC */
	struct drm_object_properties properties;

此crtc的属性跟踪。

（22）struct drm_property *scaling_filter_property

    /**
	 * @scaling_filter_property: property to apply a particular filter while
	 * scaling.
	 */
	struct drm_property *scaling_filter_property;

属性，以便在缩放时应用特定的筛选器。

（23）struct drm_crtc_state *state

    /**
	 * @state:
	 *
	 * Current atomic state for this CRTC.
	 *
	 * This is protected by @mutex. Note that nonblocking atomic commits
	 * access the current CRTC state without taking locks. Either by going
	 * through the &struct drm_atomic_state pointers, see
	 * for_each_oldnew_crtc_in_state(), for_each_old_crtc_in_state() and
	 * for_each_new_crtc_in_state(). Or through careful ordering of atomic
	 * commit operations as implemented in the atomic helpers, see
	 * &struct drm_crtc_commit.
	 */
	struct drm_crtc_state *state;

此CRTC的当前原子状态。

此项是由@mutex保护的。注意，非阻塞原子提交访问当前CRTC状态而不取得锁。或者通过遍历&struct drm_atomic_state指针（参见for_each_oldnew_crtc_in_state()、for_each_old _crtc_in.state()和for_each_new_crtc_in_state()）。或者通过对atomic helpers中实现的原子提交操作进行仔细排序（参阅&struct drm_crtc_commit）。

（24）struct list_head commit_list

    /**
	 * @commit_list:
	 *
	 * List of &drm_crtc_commit structures tracking pending commits.
	 * Protected by @commit_lock. This list holds its own full reference,
	 * as does the ongoing commit.
	 *
	 * "Note that the commit for a state change is also tracked in
	 * &drm_crtc_state.commit. For accessing the immediately preceding
	 * commit in an atomic update it is recommended to just use that
	 * pointer in the old CRTC state, since accessing that doesn't need
	 * any locking or list-walking. @commit_list should only be used to
	 * stall for framebuffer cleanup that's signalled through
	 * &drm_crtc_commit.cleanup_done."
	 */
	struct list_head commit_list;

跟踪挂起提交的&drm_crt_commit结构的列表。受@commit_lock保护。这个列表有自己的完整引用，正在进行的提交也是如此。

注意，状态更改的提交也在&drm_crtc_state.commit中进行跟踪。为了访问原子更新中紧接在前的提交，建议仅在旧CRTC状态下使用该指针，因为访问它不需要任何锁定或列表遍历。@commit_list应仅用于暂停通过&drm_crtc_commit.cleanup_done发出信号的帧缓冲区清理。

（25）spinlock_t commit_lock

    /**
	 * @commit_lock:
	 *
	 * Spinlock to protect @commit_list.
	 */
	spinlock_t commit_lock;

保护@commit_list的自旋锁。

（26）struct dentry *debugfs_entry

    /**
	 * @debugfs_entry:
	 *
	 * Debugfs directory for this CRTC.
	 */
	struct dentry *debugfs_entry;

此CRTC的debugfs目录。

（27） struct drm_crtc_crc crc

    /**
	 * @crc:
	 *
	 * Configuration settings of CRC capture.
	 */
    struct drm_crtc_crc crc;

CRC捕获的配置设置。

（28）unsigned int fence_context

    /**
	 * @fence_context:
	 *
	 * timeline context used for fence operations.
	 */
	unsigned int fence_context;

用于fence操作的时间线上下文。

（29）spinlock_t fence_lock

    /**
	 * @fence_lock:
	 *
	 * spinlock to protect the fences in the fence_context.
	 */
	spinlock_t fence_lock;

保护fence_context中的fence的spinlock。

（30）unsigned long fence_seqno

    /**
	 * @fence_seqno:
	 *
	 * Seqno variable used as monotonic counter for the fences
	 * created on the CRTC's timeline.
	 */
	unsigned long fence_seqno;

Seqno变量用作CRTC时间线上创建的fences的单调计数器。

（31）char timeline_name[32]

    /**
	 * @timeline_name:
	 *
	 * The name of the CRTC's fence timeline.
	 */
	char timeline_name[32];

CRTC的fence时间线的名称。

（32）struct drm_self_refresh_data *self_refresh_data

    /**
	 * @self_refresh_data: Holds the state for the self refresh helpers
	 *
	 * Initialized via drm_self_refresh_helper_init().
	 */
	struct drm_self_refresh_data *self_refresh_data;

保持自刷新助手的状态。

通过drm_self_refresh_helper_init()初始化。

至此，DRM CRTC的核心结构struct drm_crtc就释义完成了。后续会对此结构中涉及到的结构进行深入讲解。