Potential Exception Due to Task Priority in esp_lvgl_port with LVGL9 (BSP-596)

[nicechao]

Board

ESP32S3

Hardware Description

ESP32S3+ST7789

IDE Name

ESP-IDF5.3 + esp_lvgl_port 2.4.3 + lvgl 9.2.2

Operating System

UBUNTU24.10

Description

During code debugging, the following exception occurred:

Guru Meditation Error: Core  1 panic'ed (LoadProhibited). Exception was unhandled.

Core  1 register dump:
PC      : 0x42028d0e  PS      : 0x00060330  A0      : 0x82028d9c  A1      : 0x3fcb1aa0  
0x42028d0e: search_suitable_block at /projpath/managed_components/lvgl__lvgl/src/stdlib/builtin/lv_tlsf.c:563

A2      : 0x00000000  A3      : 0x3fcb1ac0  A4      : 0x3fcb1ac4  A5      : 0x3fcaed94  
A6      : 0x00000000  A7      : 0x00000000  A8      : 0x00000010  A9      : 0x3fcb1a80  
A10     : 0x00000003  A11     : 0x3fcb1ac0  A12     : 0x3fcb1ac4  A13     : 0x00000000  
A14     : 0x3c07d097  A15     : 0x3fcb163c  SAR     : 0x00000004  EXCCAUSE: 0x0000001c  
EXCVADDR: 0x00000014  LBEG    : 0x400556d5  LEND    : 0x400556e5  LCOUNT  : 0xfffffffd  
0x400556d5: strlen in ROM
0x400556e5: strlen in ROM

Backtrace: 0x42028d0b:0x3fcb1aa0 0x42028d99:0x3fcb1ac0 0x42028f3d:0x3fcb1af0 0x420279c4:0x3fcb1b10 0x42029100:0x3fcb1b30 0x420264b2:0x3fcb1b80 0x42019c31:0x3fcb1ba0 0x4201114a:0x3fcb1be0 0x42011680:0x3fcb1c30 0x4200adda:0x3fcb1c60 0x4200ae4b:0x3fcb1cd0 0x4037ecf9:0x3fcb1d10
0x42028d0b: search_suitable_block at managed_components/lvgl__lvgl/src/stdlib/builtin/lv_tlsf.c:563
0x42028d99: block_locate_free at managed_components/lvgl__lvgl/src/stdlib/builtin/lv_tlsf.c:769
0x42028f3d: lv_tlsf_malloc at managed_components/lvgl__lvgl/src/stdlib/builtin/lv_tlsf.c:1101
0x420279c4: lv_malloc_core at managed_components/lvgl__lvgl/src/stdlib/builtin/lv_mem_core_builtin.c:144
0x42029100: lv_malloc at managed_components/lvgl__lvgl/src/stdlib/lv_mem.c:70
0x420264b2: lv_ll_ins_head at managed_components/lvgl__lvgl/src/misc/lv_ll.c:61
0x42019c31: lv_display_create at managed_components/lvgl__lvgl/src/display/lv_display.c:64
0x4201114a: lvgl_port_add_disp_priv at managed_components/espressif__esp_lvgl_port/src/lvgl9/esp_lvgl_port_disp.c:321
0x42011680: lvgl_port_add_disp at managed_components/espressif__esp_lvgl_port/src/lvgl9/esp_lvgl_port_disp.c:87
0x420110b0: lvgl_port_add_disp at managed_components/espressif__esp_lvgl_port/src/lvgl9/esp_lvgl_port_disp.c:87

The assembly code corresponding to the exception:

static block_header_t * search_suitable_block(control_t * control, int * fli, int * sli)
42028d00 <search_suitable_block>:
{
42028d00:       004136          entry   a1, 32
    int fl = *fli;
42028d03:       002372          l32i    a7, a3, 0
    int sl = *sli;
42028d06:       0024a2          l32i    a10, a4, 0
    unsigned int sl_map = control->sl_bitmap[fl] & (~0U << sl);
42028d09:       874b            addi.n  a8, a7, 4
42028d0b:       a08820          addx4   a8, a8, a2
42028d0e:       1898            l32i.n  a9, a8, 4
42028d10:       f87c            movi.n  a8, -1
42028d12:       401a00          ssl     a10
42028d15:       a18800          sll     a8, a8
42028d18:       10a980          and     a10, a9, a8
    if(!sl_map) {
42028d1b:       398987          bany    a9, a8, 42028d58 <search_suitable_block+0x58>
        const unsigned int fl_map = control->fl_bitmap & (~0U << (fl + 1));
42028d1e:       4298            l32i.n  a9, a2, 16
42028d20:       771b            addi.n  a7, a7, 1
42028d22:       f87c            movi.n  a8, -1
42028d24:       401700          ssl     a7
42028d27:       a18800          sll     a8, a8
42028d2a:       10a980          and     a10, a9, a8

The cause of the exception is that the control parameter was not properly initialized and was actually a null pointer.

The root cause was traced back to the initialization process:

• According to the documentation, the initialization should first call lvgl_port_init() and then lvgl_port_add_disp().
• When using LVGL8, the lv_init() function is directly called within lvgl_port_init(), and the program runs normally.
• However, when using LVGL9, the lv_init() function is scheduled to run within the lvgl_port_task(), a task created by lvgl_port_init(). If the priority of lvgl_port_task() is lower than the current task, the lv_init() function may not have been executed by the time lvgl_port_add_disp() calls the LVGL9 API, which can lead to the exception.

Sketch

static esp_err_t app_lvgl_init(void)
{
    /* Initialize LVGL */
    const lvgl_port_cfg_t lvgl_cfg = {
        .task_priority = 4,         /* LVGL task priority */
        .task_stack = 4096,         /* LVGL task stack size */
        .task_affinity = -1,        /* LVGL task pinned to core (-1 is no affinity) */
        .task_max_sleep_ms = 500,   /* Maximum sleep in LVGL task */
        .timer_period_ms = 5        /* LVGL timer tick period in ms */
    };
    ESP_RETURN_ON_ERROR(lvgl_port_init(&lvgl_cfg), TAG, "LVGL port initialization failed");

    /* Add LCD screen */
    ESP_LOGD(TAG, "Add LCD screen");
    const lvgl_port_display_cfg_t disp_cfg = {
        .io_handle = lcd_io,
        .panel_handle = lcd_panel,
        .buffer_size = EXAMPLE_LCD_H_RES * EXAMPLE_LCD_DRAW_BUFF_HEIGHT * sizeof(uint16_t),
        .double_buffer = EXAMPLE_LCD_DRAW_BUFF_DOUBLE,
        .hres = EXAMPLE_LCD_H_RES,
        .vres = EXAMPLE_LCD_V_RES,
        .monochrome = false,
        /* Rotation values must be same as used in esp_lcd for initial settings of the screen */
        .rotation = {
            .swap_xy = false,
            .mirror_x = true,
            .mirror_y = true,
        },
        .flags = {
            .buff_dma = true,
#if LVGL_VERSION_MAJOR >= 9
            .swap_bytes = true,
#endif
        }
    };
    lvgl_disp = lvgl_port_add_disp(&disp_cfg);

    /* Add touch input (for selected screen) */
    const lvgl_port_touch_cfg_t touch_cfg = {
        .disp = lvgl_disp,
        .handle = touch_handle,
    };
    lvgl_touch_indev = lvgl_port_add_touch(&touch_cfg);

    return ESP_OK;
}

static void lvgl_task(void *arg)
{
    app_lvgl_init();
}

xTaskCreate(lvgl_task, TAG, 4 * 1024, NULL, 5, NULL);

Other Steps to Reproduce

Suggested Solution:

• The documentation should be updated to include a reminder about task priority.
• Alternatively, it could be ensured that lvgl_port_add_disp() only runs after lv_init() has been completed.

I have checked existing issues, README.md and ESP32 Forum

• I confirm I have checked existing issues, online documentation and Troubleshooting guide.