[rk3288][Android7.1]重启后无法显示kernel logo

问题描述

系统重启后可以显示uboot logo， kernel logo 无法显示

问题分析

在kernel中添加log，各个参数值如下：

[gyl] setup_initial_state:496 mode->hdisplay = 720
[gyl] setup_initial_state:497 mode->vdisplay = 1280
[gyl] setup_initial_state:498 mode->crtc_hsync_end 726
[gyl] setup_initial_state:499 mode->crtc_vsync_end 1299
[gyl] setup_initial_state:500 mode->vrefresh = 76
[gyl] setup_initial_state:501 mode->flags = 2147483654d
[gyl] setup_initial_state:502
[gyl] setup_initial_state:503 set->hdisplay = 720
[gyl] setup_initial_state:504 set->vdisplay = 1280
[gyl] setup_initial_state:505 set->crtc_hsync_end = 726
[gyl] setup_initial_state:506 set->crtc_vsync_end = 1299
[gyl] setup_initial_state:507 set->vrefresh = 76
[gyl] setup_initial_state:508 set->flags = 6d
[gyl] show_loader_logo:772

其中mode->flags = 2147483654d 明显存在异常，根据代码只有所有参数与uboot里的配置相同时才能正常显示。

list_for_each_entry(mode, &connector->modes, head) {
		if (mode->hdisplay == set->hdisplay &&
		    mode->vdisplay == set->vdisplay &&
		    mode->crtc_hsync_end == set->crtc_hsync_end &&
		    mode->crtc_vsync_end == set->crtc_vsync_end &&
		    drm_mode_vrefresh(mode) == set->vrefresh &&
		    mode->flags == set->flags) {
			found = 1;
			match = 1;
			break;
		}
	}

解决方法

• 这些参数可在dts中配置，kernel的代码中会读取这些参数

  if (!of_property_read_u32(route, "video,hdisplay", &val))
         set->hdisplay = val;
  
  if (!of_property_read_u32(route, "video,vdisplay", &val))
         set->vdisplay = val;
  
  if (!of_property_read_u32(route, "video,crtc_hsync_end", &val))
         set->crtc_hsync_end = val;
  
  if (!of_property_read_u32(route, "video,crtc_vsync_end", &val))
         set->crtc_vsync_end = val;
  
  if (!of_property_read_u32(route, "video,vrefresh", &val))
         set->vrefresh = val;
  
  if (!of_property_read_u32(route, "video,flags", &val))
         set->flags = val;
  
         ......

• android 5.1代码中没有对flags进行判断，最简单的修改方式就是去掉flags的判断。

---

## patch

diff --git a/kernel/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/kernel/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index c24c6d9..28e4e38 100644 (file)
--- a/kernel/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/kernel/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -494,8 +494,7 @@ static int setup_initial_state(struct drm_device *drm_dev,
                    mode->vdisplay == set->vdisplay &&
                    mode->crtc_hsync_end == set->crtc_hsync_end &&
                    mode->crtc_vsync_end == set->crtc_vsync_end &&
-                   drm_mode_vrefresh(mode) == set->vrefresh &&
-                   mode->flags == set->flags) {
+                   drm_mode_vrefresh(mode) == set->vrefresh) {
                        found = 1;
                        match = 1;
                        break;