Android 8.1 Display System源码分析（4）：DRM/KMS分析（RK3399）

注：文章都是通过阅读 Android && Linux 平台源码、各位前辈总结的资料、加上自己的思考分析总结出来的，其中难免有理不对的地方，欢迎大家批评指正。文章为个人学习、研究、欣赏之用。图文内容、源码整理自互联网，如有侵权，请联系删除（◕‿◕），转载请注明出处（ ©Android @Linux @Rockchip版权所有），谢谢(๑乛◡乛๑) 、（ ͡° ͜ʖ ͡°）、（ಡωಡ）！！！。
（==文章基于 Kernel-4.4==）&&（==文章基于 Android-8.1==）
【开发板 - Firefly-RK3399 7.85寸1024x768显示屏模组（MIPI接口）】

正是由于前人的分析和总结，帮助我节约了大量的时间和精力，特别感谢！！！

（1）【DRM（Direct Rendering Manager）学习简介】

（2）【The DRM/KMS subsystem from a newbie’s point of view】

（3）【Anatomy of an Atomic KMS Driver】

（4）【Why and How to use KMS】

---

==源码（部分）==

DRM

• I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip*
• I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm*
• I:\RK3399_Android8.1_MIPI\kernel\drivers\phy\rockchip*

---

(一)、DRM/KMS简介

（1）、DRM（Direct Rendering Manager）简介

DRM 是 Linux 目前主流的图形显示框架，相比 FB 架构，DRM 更能适应当前日益更新的显示硬件。比如 FB 原生不支持多层合成，不支持 VSYNC，不支持 DMA-BUF，不支持异步更新，不支持 fence 机制等等，而这些功能 DRM 原生都支持。同时 DRM 可以统一管理 GPU 和 Display 驱动，使得软件架构更为统一，方便管理和维护。

DRM 从模块上划分，可以简单分为 3 部分：**libdrm、KMS、GEM**

1.1、libdrm

对底层接口进行封装，向上层提供通用的 API 接口，主要是对各种 IOCTL 接口进行封装。

1.2、GEM

Graphic Execution Manager，主要负责显示 buffer 的分配和释放，也是 GPU 唯一用到 DRM 的地方。

1.3、基本元素

---

DRM 框架涉及到的元素很多，大致如下：
KMS：**CRTC，ENCODER，CONNECTOR，PLANE，FB，VBLANK，property**
GEM：**DUMB、PRIME、fence**

元素	说明
CRTC	对显示 buffer 进行扫描，并产生时序信号的硬件模块，通常指 Display Controller
ENCODER	负责将 CRTC 输出的 timing 时序转换成外部设备所需要的信号的模块，如 HDMI 转换器或 DSI Controller
CONNECTOR	连接物理显示设备的连接器，如 HDMI、DisplayPort、DSI 总线，通常和 Encoder 驱动绑定在一起
PLANE	硬件图层，有的 Display 硬件支持多层合成显示，但所有的 Display Controller 至少要有 1 个 plane
FB	Framebuffer，单个图层的显示内容，唯一一个和硬件无关的基本元素
VBLANK	软件和硬件的同步机制，RGB 时序中的垂直消影区，软件通常使用硬件 VSYNC 来实现
property	任何你想设置的参数，都可以做成 property，是 DRM 驱动中最灵活、最方便的 Mode setting 机制
DUMB	只支持连续物理内存，基于 kernel 中通用 CMA API 实现，多用于小分辨率简单场景
PRIME	连续、非连续物理内存都支持，基于 DMA-BUF 机制，可以实现 buffer 共享，多用于大内存复杂场景
fence	buffer 同步机制，基于内核 dma_fence 机制实现，用于防止显示内容出现异步问题

（2）、KMS

Kernel Mode Setting，所谓 Mode setting，其实说白了就两件事：更新画面和设置显示参数。
更新画面：显示 buffer 的切换，多图层的合成方式，以及每个图层的显示位置。
设置显示参数：包括分辨率、刷新率、电源状态（休眠唤醒）等。

(二)、DRM/KMS驱动分析

首先看看RK3399 DRM Kernel启动框图：

首先看看RK3399DRM Kernel启动UML流程图：

（1）、Drm device创建注册

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c
static int rockchip_drm_bind(struct device *dev)
{
    struct drm_device *drm_dev;
    struct rockchip_drm_private *private;
    int ret;
    struct device_node *np = dev->of_node;
    struct device_node *parent_np;
    struct drm_crtc *crtc;
    printk("zjj.sye.display rockchip_drm_drv.c rockchip_drm_bind \n");
    //drm_dev_alloc 分配
    drm_dev = drm_dev_alloc(&rockchip_drm_driver, dev);

    ret = drm_dev_set_unique(drm_dev, "%s", dev_name(dev));

    dev_set_drvdata(dev, drm_dev);

    private = devm_kzalloc(drm_dev->dev, sizeof(*private), GFP_KERNEL);

    mutex_init(&private->commit_lock);
    INIT_WORK(&private->commit_work, rockchip_drm_atomic_work);

    drm_dev->dev_private = private;

    private->dmc_support = false;
    private->devfreq = devfreq_get_devfreq_by_phandle(dev, 0);

    private->hdmi_pll.pll = devm_clk_get(dev, "hdmi-tmds-pll");

    private->default_pll.pll = devm_clk_get(dev, "default-vop-pll");

#ifdef CONFIG_DRM_DMA_SYNC
    private->cpu_fence_context = fence_context_alloc(1);
    atomic_set(&private->cpu_fence_seqno, 0);
#endif

    ret = rockchip_drm_init_iommu(drm_dev);

    drm_mode_config_init(drm_dev);

    rockchip_drm_mode_config_init(drm_dev);
    rockchip_drm_create_properties(drm_dev);

    /* Try to bind all sub drivers. */
    ret = component_bind_all(dev, drm_dev);

    rockchip_attach_connector_property(drm_dev);

    ret = drm_vblank_init(drm_dev, drm_dev->mode_config.num_crtc);

    drm_mode_config_reset(drm_dev);

    rockchip_drm_set_property_default(drm_dev);
    drm_dev->irq_enabled = true;
    drm_kms_helper_poll_init(drm_dev);
    drm_dev->vblank_disable_allowed = true;

    rockchip_gem_pool_init(drm_dev);
#ifndef MODULE
    show_loader_logo(drm_dev);
#endif
    ret = of_reserved_mem_device_init(drm_dev->dev);

    ret = rockchip_drm_fbdev_init(drm_dev);

    drm_for_each_crtc(crtc, drm_dev) {
        struct drm_fb_helper *helper = private->fbdev_helper;
        struct rockchip_crtc_state *s = NULL;

        s = to_rockchip_crtc_state(crtc->state);
        if (is_support_hotplug(s->output_type)) {
            s->crtc_primary_fb = crtc->primary->fb;
            crtc->primary->fb = helper->fb;
            drm_framebuffer_reference(helper->fb);
        }
    }
    drm_dev->mode_config.allow_fb_modifiers = true;
    //drm_dev注册
    ret = drm_dev_register(drm_dev, 0);
 }

（2）、Drm driver信息

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c
static struct drm_driver rockchip_drm_driver = {
    .driver_features    = DRIVER_MODESET | DRIVER_GEM |
                  DRIVER_PRIME | DRIVER_ATOMIC |
                  DRIVER_RENDER,
    .preclose        = rockchip_drm_preclose,
    .lastclose        = rockchip_drm_lastclose,
    .get_vblank_counter    = drm_vblank_no_hw_counter,
    .open            = rockchip_drm_open,
    .postclose        = rockchip_drm_postclose,
    .enable_vblank        = rockchip_drm_crtc_enable_vblank,
    .disable_vblank        = rockchip_drm_crtc_disable_vblank,
    .gem_vm_ops        = &rockchip_drm_vm_ops,
    .gem_free_object    = rockchip_gem_free_object,
    .dumb_create        = rockchip_gem_dumb_create,
    .dumb_map_offset    = rockchip_gem_dumb_map_offset,
    .dumb_destroy        = drm_gem_dumb_destroy,
    .prime_handle_to_fd    = drm_gem_prime_handle_to_fd,
    .prime_fd_to_handle    = drm_gem_prime_fd_to_handle,
    .gem_prime_import    = drm_gem_prime_import,
    .gem_prime_export    = drm_gem_prime_export,
    .gem_prime_get_sg_table    = rockchip_gem_prime_get_sg_table,
    .gem_prime_import_sg_table    = rockchip_gem_prime_import_sg_table,
    .gem_prime_vmap        = rockchip_gem_prime_vmap,
    .gem_prime_vunmap    = rockchip_gem_prime_vunmap,
    .gem_prime_mmap        = rockchip_gem_mmap_buf,
    .gem_prime_begin_cpu_access = rockchip_gem_prime_begin_cpu_access,
    .gem_prime_end_cpu_access = rockchip_gem_prime_end_cpu_access,
#ifdef CONFIG_DEBUG_FS
    .debugfs_init        = rockchip_drm_debugfs_init,
    .debugfs_cleanup    = rockchip_drm_debugfs_cleanup,
#endif
    .ioctls            = rockchip_ioctls,
    .num_ioctls        = ARRAY_SIZE(rockchip_ioctls),
    .fops            = &rockchip_drm_driver_fops,
    .name    = DRIVER_NAME,
    .desc    = DRIVER_DESC,
    .date    = DRIVER_DATE,
    .major    = DRIVER_MAJOR,
    .minor    = DRIVER_MINOR,
};

（3）、Drm driver file operations

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c
static const struct file_operations rockchip_drm_driver_fops = {
    .owner = THIS_MODULE,
    .open = drm_open,
    .mmap = rockchip_gem_mmap,
    .poll = drm_poll,
    .read = drm_read,
    .unlocked_ioctl = drm_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl = drm_compat_ioctl,
#endif
    .release = drm_release,
};

（4）、Mode Config

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c
static int rockchip_drm_bind(struct device *dev)
{
drm_mode_config_init(drm_dev);
rockchip_drm_mode_config_init(drm_dev);
}

I:\RK3399_Android8.1_MIPI\kernel\arch\arm64\boot\dts\rockchip\rk3399-firefly-mipi.dts

void rockchip_drm_mode_config_init(struct drm_device *dev)
{
    dev->mode_config.min_width = 0;
    dev->mode_config.min_height = 0;
    dev->mode_config.max_width = 8192;
    dev->mode_config.max_height = 8192;

    dev->mode_config.funcs = &rockchip_drm_mode_config_funcs;
}

static const struct drm_mode_config_funcs rockchip_drm_mode_config_funcs = {
    .fb_create = rockchip_user_fb_create,
    .output_poll_changed = rockchip_drm_output_poll_changed,
    .atomic_check = drm_atomic_helper_check,
    .atomic_commit = rockchip_drm_atomic_commit,
};

（5）、GEM

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c
const struct vm_operations_struct rockchip_drm_vm_ops = {
    .open = drm_gem_vm_open,
    .close = drm_gem_vm_close,
};

（6）、GEM – Dumb

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c

static struct drm_driver rockchip_drm_driver = {
    .driver_features    = DRIVER_MODESET | DRIVER_GEM |
                  DRIVER_PRIME | DRIVER_ATOMIC |
                  DRIVER_RENDER,
    ......
    .dumb_create        = rockchip_gem_dumb_create,
    .dumb_map_offset    = rockchip_gem_dumb_map_offset,
    .dumb_destroy        = drm_gem_dumb_destroy,
    ......
};

（7）、GEM – PRIME

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c

static struct drm_driver rockchip_drm_driver = {
    .driver_features    = DRIVER_MODESET | DRIVER_GEM |
                  DRIVER_PRIME | DRIVER_ATOMIC |
                  DRIVER_RENDER,
    ......
    .prime_handle_to_fd    = drm_gem_prime_handle_to_fd,
    .prime_fd_to_handle    = drm_gem_prime_fd_to_handle,
    .gem_prime_import    = drm_gem_prime_import,
    .gem_prime_export    = drm_gem_prime_export,
    .gem_prime_get_sg_table    = rockchip_gem_prime_get_sg_table,
    .gem_prime_import_sg_table    = rockchip_gem_prime_import_sg_table,
    .gem_prime_vmap        = rockchip_gem_prime_vmap,
    .gem_prime_vunmap    = rockchip_gem_prime_vunmap,
    .gem_prime_mmap        = rockchip_gem_mmap_buf,
    .gem_prime_begin_cpu_access = rockchip_gem_prime_begin_cpu_access,
    .gem_prime_end_cpu_access = rockchip_gem_prime_end_cpu_access,
    ......
};

（8）、Frame Buffer

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_fb.c

static const struct drm_mode_config_funcs rockchip_drm_mode_config_funcs = {
    .fb_create = rockchip_user_fb_create,
    .output_poll_changed = rockchip_drm_output_poll_changed,
    .atomic_check = drm_atomic_helper_check,
    .atomic_commit = rockchip_drm_atomic_commit,
};

static struct drm_framebuffer *
rockchip_user_fb_create(struct drm_device *dev, struct drm_file *file_priv,
            struct drm_mode_fb_cmd2 *mode_cmd)
{
    struct drm_framebuffer *fb;
    struct drm_gem_object *objs[ROCKCHIP_MAX_FB_BUFFER];
    struct drm_gem_object *obj;
    unsigned int hsub;
    unsigned int vsub;
    int num_planes;
    int ret;
    int i;

    hsub = drm_format_horz_chroma_subsampling(mode_cmd->pixel_format);
    vsub = drm_format_vert_chroma_subsampling(mode_cmd->pixel_format);
    num_planes = min(drm_format_num_planes(mode_cmd->pixel_format),
             ROCKCHIP_MAX_FB_BUFFER);

    for (i = 0; i < num_planes; i++) {
        unsigned int width = mode_cmd->width / (i ? hsub : 1);
        unsigned int height = mode_cmd->height / (i ? vsub : 1);
        unsigned int min_size;
        unsigned int bpp =
            drm_format_plane_bpp(mode_cmd->pixel_format, i);

        obj = drm_gem_object_lookup(dev, file_priv,
                        mode_cmd->handles[i]);
        if (!obj) {
            dev_err(dev->dev, "Failed to lookup GEM object\n");
            ret = -ENXIO;
            goto err_gem_object_unreference;
        }

        min_size = (height - 1) * mode_cmd->pitches[i] +
            mode_cmd->offsets[i] + roundup(width * bpp, 8) / 8;
        if (obj->size < min_size) {
            DRM_ERROR("Invalid Gem size on plane[%d]: %zd < %d\n",
                  i, obj->size, min_size);
            drm_gem_object_unreference_unlocked(obj);
            ret = -EINVAL;
            goto err_gem_object_unreference;
        }
        objs[i] = obj;
    }

    fb = rockchip_fb_alloc(dev, mode_cmd, objs, NULL, i);
    ......

    return fb;
}

（9）、Initialization – CRTC

static int vop_bind(struct device *dev, struct device *master, void *data)
{
    struct platform_device *pdev = to_platform_device(dev);
    const struct vop_data *vop_data;
    struct drm_device *drm_dev = data;
    struct vop *vop;
    struct resource *res;
    ......

    ret = vop_create_crtc(vop);
    ......
    of_rockchip_drm_sub_backlight_register(dev, &vop->crtc,
                           &rockchip_sub_backlight_ops);

    return 0;
}


static int vop_create_crtc(struct vop *vop)
{
    struct device *dev = vop->dev;
    const struct vop_data *vop_data = vop->data;
    struct drm_device *drm_dev = vop->drm_dev;
    struct rockchip_drm_private *private = drm_dev->dev_private;
    struct drm_plane *primary = NULL, *cursor = NULL, *plane, *tmp;
    struct drm_crtc *crtc = &vop->crtc;
    struct device_node *port;
    
    /*
     * Create drm_plane for primary and cursor planes first, since we need
     * to pass them to drm_crtc_init_with_planes, which sets the
     * "possible_crtcs" to the newly initialized crtc.
     */
    for (i = 0; i < vop->num_wins; i++) {
        struct vop_win *win = &vop->win[i];
       ......

        ret = vop_plane_init(vop, win, 0);
        ......

    }

    ret = drm_crtc_init_with_planes(drm_dev, crtc, primary, cursor,
                    &vop_crtc_funcs, NULL);
    .......
    drm_crtc_helper_add(crtc, &vop_crtc_helper_funcs);

    ......

    init_completion(&vop->dsp_hold_completion);
    init_completion(&vop->line_flag_completion);
    crtc->port = port;
    rockchip_register_crtc_funcs(crtc, &private_crtc_funcs);
    .......
}

（10）、Initialization – Encoder

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\dw-mipi-dsi.c

static int dw_mipi_dsi_register(struct drm_device *drm,
                      struct dw_mipi_dsi *dsi)
{
    struct drm_encoder *encoder = &dsi->encoder;
    struct drm_connector *connector = &dsi->connector;
    struct device *dev = dsi->dev;
    int ret;
   printk("zjj.sye.display dw_mipi_dsi.c dw_mipi_dsi_register\n");
    encoder->possible_crtcs = drm_of_find_possible_crtcs(drm,
                                 dev->of_node);
    /*
     * If we failed to find the CRTC(s) which this encoder is
     * supposed to be connected to, it's because the CRTC has
     * not been registered yet.  Defer probing, and hope that
     * the required CRTC is added later.
     */
    if (encoder->possible_crtcs == 0)
        return -EPROBE_DEFER;

    drm_encoder_helper_add(&dsi->encoder,
                   &dw_mipi_dsi_encoder_helper_funcs);
    ret = drm_encoder_init(drm, &dsi->encoder, &dw_mipi_dsi_encoder_funcs,
             DRM_MODE_ENCODER_DSI, NULL);
    ......
    return 0;
}

（11）、Initialization – Connector

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\dw-mipi-dsi.c

static int dw_mipi_dsi_register(struct drm_device *drm,
                      struct dw_mipi_dsi *dsi)
{
    struct drm_encoder *encoder = &dsi->encoder;
    struct drm_connector *connector = &dsi->connector;
    struct device *dev = dsi->dev;
    int ret;

    ......

    /* If there's a bridge, attach to it and let it create the connector. */
    if (dsi->bridge) {
        ......
    /* Otherwise create our own connector and attach to a panel */
    } else {
        dsi->connector.port = dev->of_node;
        ret = drm_connector_init(drm, &dsi->connector,
                     &dw_mipi_dsi_atomic_connector_funcs,
                     DRM_MODE_CONNECTOR_DSI);
        ......
        drm_connector_helper_add(connector,
                     &dw_mipi_dsi_connector_helper_funcs);
        drm_mode_connector_attach_encoder(connector, encoder);

        ret = drm_panel_attach(dsi->panel, &dsi->connector);
        ......
    }

    return 0;
}

（12）、Initialization – Plane

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\panel\panel-simple.c

static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
{
    struct device_node *backlight, *ddc;
    struct panel_simple *panel;
    struct panel_desc *of_desc;
    const char *cmd_type;
    u32 val;
    ......
    panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
    ......

    drm_panel_init(&panel->base);
    panel->base.dev = dev;
    panel->base.funcs = &panel_simple_funcs;

    err = drm_panel_add(&panel->base);
    if (err < 0)
        goto free_ddc;

    dev_set_drvdata(dev, panel);

    return 0;
}

（13）、Modes Discovery

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\dw-mipi-dsi.c

static const struct drm_connector_funcs dw_mipi_dsi_atomic_connector_funcs = {
    .dpms = drm_atomic_helper_connector_dpms,
    .fill_modes = drm_helper_probe_single_connector_modes,
    .detect = dw_mipi_dsi_detect,
    .destroy = dw_mipi_dsi_drm_connector_destroy,
    .reset = drm_atomic_helper_connector_reset,
    .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
    .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};

static const struct drm_connector_helper_funcs
dw_mipi_dsi_connector_helper_funcs = {
    .loader_protect = dw_mipi_loader_protect,
    .get_modes = dw_mipi_dsi_connector_get_modes,
    .best_encoder = dw_mipi_dsi_connector_best_encoder,
};

（14）、State – CRTC

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_vop.c

static const struct drm_crtc_funcs vop_crtc_funcs = {
    ......
    .atomic_duplicate_state = vop_crtc_duplicate_state,
    .atomic_destroy_state = vop_crtc_destroy_state,
};

（15）、State – Connector

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\dw-mipi-dsi.c

static const struct drm_connector_funcs dw_mipi_dsi_atomic_connector_funcs = {
    ......
    .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
    .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};

（16）、Atomic Update – KMS

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\dw-mipi-dsi.c
static const struct drm_mode_config_funcs rockchip_drm_mode_config_funcs = {
    .......
    .atomic_check = drm_atomic_helper_check,
    .atomic_commit = rockchip_drm_atomic_commit,
};

（17）、Atomic Update – CRTC

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_vop.c
static const struct drm_crtc_helper_funcs vop_crtc_helper_funcs = {
    .load_lut = vop_crtc_load_lut,
    .enable = vop_crtc_enable,
    .disable = vop_crtc_disable,
    .mode_fixup = vop_crtc_mode_fixup,
    .atomic_check = vop_crtc_atomic_check,
    .atomic_flush = vop_crtc_atomic_flush,
    .atomic_begin = vop_crtc_atomic_begin,
};

（18）、Atomic Update – Encoder

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\dw-mipi-dsi.c

static const struct drm_encoder_helper_funcs
dw_mipi_dsi_encoder_helper_funcs = {
    .mode_fixup = dw_mipi_dsi_encoder_mode_fixup,
    .mode_set = dw_mipi_dsi_encoder_mode_set,
    .enable = dw_mipi_dsi_encoder_enable,
    .disable = dw_mipi_dsi_encoder_disable,
    .atomic_check = dw_mipi_dsi_encoder_atomic_check,
};

（19）、Atomic Update – CRTC+Plane

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_vop.c


static const struct drm_plane_helper_funcs plane_helper_funcs = {
    .prepare_fb = vop_plane_prepare_fb,
    .cleanup_fb = vop_plane_cleanup_fb,
    .atomic_check = vop_plane_atomic_check,
    .atomic_update = vop_plane_atomic_update,
    .atomic_disable = vop_plane_atomic_disable,
};

（20）、Vertical Blanking

I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_drv.c

static struct drm_driver rockchip_drm_driver = {
    .driver_features    = DRIVER_MODESET | DRIVER_GEM |
                  DRIVER_PRIME | DRIVER_ATOMIC |
                  DRIVER_RENDER,
    ......
    .enable_vblank        = rockchip_drm_crtc_enable_vblank,
    .disable_vblank        = rockchip_drm_crtc_disable_vblank,
 }
 
 I:\RK3399_Android8.1_MIPI\kernel\drivers\gpu\drm\rockchip\rockchip_drm_vop.c
 static int vop_crtc_enable_vblank(struct drm_crtc *crtc)
{
    struct vop *vop = to_vop(crtc);
    unsigned long flags;

    ......

    spin_lock_irqsave(&vop->irq_lock, flags);

    if (VOP_MAJOR(vop->version) == 3 && VOP_MINOR(vop->version) >= 7) {
        VOP_INTR_SET_TYPE(vop, clear, FS_FIELD_INTR, 1);
        VOP_INTR_SET_TYPE(vop, enable, FS_FIELD_INTR, 1);
    } else {
        VOP_INTR_SET_TYPE(vop, clear, FS_INTR, 1);
        VOP_INTR_SET_TYPE(vop, enable, FS_INTR, 1);
    }

    spin_unlock_irqrestore(&vop->irq_lock, flags);

    return 0;
}

（三）、参考资料(特别感谢)：

（1）【DRM（Direct Rendering Manager）学习简介】

（2）【The DRM/KMS subsystem from a newbie’s point of view】

（3）【Anatomy of an Atomic KMS Driver】

（4）【Why and How to use KMS】