buildroot开机时DSI屏幕变成跟uart一样输出log，现在想显示logo
1、failed to show loader logo
[ 2.467479] mmcblk1: p1 p2 p3 p4 p5 p6 p7 p8 p9
[ 2.468827] rockchip-drm display-subsystem: can't not find any loader display
[ 2.468859] rockchip-drm display-subsystem: failed to show loader logo
[ 2.472110] rockchip-vop ff8f0000.vop: [drm:vop_crtc_atomic_enable] Update mode to 1024x600p75, type: 16
[ 2.472439] dw-mipi-dsi ff960000.dsi: [drm:dw_mipi_dsi_encoder_enable] final DSI-Link bandwidth: 504 x 4 Mbps
[ 2.474823] panel_simple_prepare p->prepared=1
[ 2.474828] sn65dsi84_is_connected sn65dsi84 connect = 0
[ 2.474834] panel_simple_enable p->enabled=1static void show_loader_logo(struct drm_device *drm_dev)
添加打印看看情况
@@ -993,21 +993,27 @@ static void show_loader_logo(struct drm_device *drm_dev)state->acquire_ctx = mode_config->acquire_ctx;for_each_child_of_node(root, route) {
- if (!of_device_is_available(route))
+ if (!of_device_is_available(route)) {
+ dev_warn(drm_dev->dev, "route->name=%s not available, route->type=%s, route->full_name=%s\n", route->name, route->type, route->full_name);continue;
+ }set = of_parse_display_resource(drm_dev, route);
- if (!set)
+ if (!set) {
+ dev_warn(drm_dev->dev, "route->name=%s not set\n", route->name);continue;
+ }if (setup_initial_state(drm_dev, state, set)) {drm_framebuffer_put(set->fb);INIT_LIST_HEAD(&set->head);list_add_tail(&set->head, &mode_unset_list);
+ dev_warn(drm_dev->dev, "route->name=%s add to mode_unset_list\n", route->name);continue;}INIT_LIST_HEAD(&set->head);list_add_tail(&set->head, &mode_set_list);
+ dev_warn(drm_dev->dev, "route->name=%s add to mode_set_list\n", route->name);}/*
@@ -1020,6 +1026,7 @@ static void show_loader_logo(struct drm_device *drm_dev)list_for_each_entry_safe(set, tmp_set, &mode_set_list, head) {if (set->crtc == unset->crtc) {
+ dev_warn(drm_dev->dev, "find_used_crtc:%s\n", set->crtc->name);find_used_crtc = 1;continue;}
@@ -1031,6 +1038,7 @@ static void show_loader_logo(struct drm_device *drm_dev)struct rockchip_drm_private *priv =drm_dev->dev_private;+ dev_warn(drm_dev->dev, "unset crtc:%s\n", crtc->name);if (unset->hdisplay && unset->vdisplay) {if (priv->crtc_funcs[pipe] &&priv->crtc_funcs[pipe]->loader_protect)加了打印后就有了这些输出，不过还是没看到kernel的logo，继续查找Console: switching
2、Console: switching
[ 2.443211] rockchip-drm display-subsystem: route->name=route-dsi add to mode_set_list
[ 2.467159] Freeing drm_logo memory: 260K
[ 2.482948] Console: switching to colour frame buffer device 128x37
[ 2.497465] usb 3-1: New USB device found, idVendor=05e3, idProduct=06Populating /dev using udev: 10, bcdDevice=93.11
[ 2.497480] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[ 2.497492] usb 3-1: Product: USB2.1 Hub
[ 2.497502] usb 3-1: Manufacturer:
[ 2.502957] rockchip-drm display-subsystem: fb0: frame buffer device添加dump_stack()查看调用过程
+++ b/drivers/tty/vt/vt.c
@@ -3562,6 +3562,8 @@ static int do_bind_con_driver(const struct consw *csw, int first, int last,clear_buffer_attributes(vc);}+ dump_stack();
+pr_info("Console: switching ");[ 2.452309] Freeing drm_logo memory: 260K
[ 2.468135] CPU: 4 PID: 43 Comm: kworker/4:1 Not tainted 4.19.193 #17
[ 2.468138] Hardware name: ASUS Tinker Board 2Populating /dev using udev: /2S (DT)
[ 2.468152] Workqueue: events deferred_probe_work_func
[ 2.468156] Call trace:
[ 2.468163] dump_backtrace+0x0/0x188
[ 2.468167] show_stack+0x24/0x30
[ 2.468173] dump_stack+0x8c/0xb4
[ 2.468179] do_bind_con_driver+0x140/0x2f4
[ 2.468182] do_take_over_console+0x194/0x1d8
[ 2.468186] do_fbcon_takeover+0x78/0xe0
[ 2.468189] fbcon_event_notify+0x458/0x898
[ 2.468194] notifier_call_chain+0x70/0x90
[ 2.468197] __blocking_notifier_call_chain+0x58/0x84
[ 2.468201] blocking_notifier_call_chain+0x3c/0x4c
[ 2.468206] fb_notifier_call_chain+0x30/0x3c
[ 2.468209] register_framebuffer+0x2b4/0x2ec
[ 2.468214] __drm_fb_helper_initial_config_and_unlock+0x2b8/0x360
[ 2.468218] drm_fb_helper_initial_config+0x3c/0x50
[ 2.468223] rockchip_drm_fbdev_init+0xf0/0x120
[ 2.468227] rockchip_drm_bind+0x550/0x1958
[ 2.468232] try_to_bring_up_master+0x224/0x270
[ 2.468235] component_add+0xe4/0x13c
[ 2.468238] cdn_dp_probe+0x1b0/0x1c0
[ 2.468242] platform_drv_probe+0x58/0xa4
[ 2.468245] really_probe+0x2a8/0x3a4
[ 2.468248] driver_probe_device+0x124/0x134
[ 2.468251] __device_attach_driver+0xc8/0x100
[ 2.468254] bus_for_each_drv+0xb0/0xd4
[ 2.468257] __device_attach+0xdc/0x16c
[ 2.468260] device_initial_probe+0x24/0x30
[ 2.468262] bus_probe_device+0x38/0x98
[ 2.468265] deferred_probe_work_func+0xb8/0xcc
[ 2.468269] process_one_work+0x200/0x330
[ 2.468272] worker_thread+0x258/0x2fc
[ 2.468275] kthread+0x120/0x130
[ 2.468279] ret_from_fork+0x10/0x18
[ 2.468281] Console: switching to colour frame buffer device 128x37从rockchip_drm_bind分析，刚好执行完show_loader_logo后就到rockchip_drm_fbdev_init
执行到nb->notifier_call(nb, val, v);也就是fbcon_event_notify(struct notifier_block *self, unsigned long action, void *data)
kernel/drivers/video/fbdev/core/Makefile有CONFIG_FRAMEBUFFER_CONSOLE宏用来编译fbcon.o的，直接屏蔽
@@ -796,4 +796,4 @@ CONFIG_VT=yCONFIG_DUMMY_CONSOLE=yCONFIG_DUMMY_CONSOLE_COLUMNS=80CONFIG_DUMMY_CONSOLE_ROWS=25
-CONFIG_FRAMEBUFFER_CONSOLE=y
+# CONFIG_FRAMEBUFFER_CONSOLE is not set3、正常显示
buildroot显示kernel logo
：线程状态，线程安全)
