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feat(lcd): ST7796 Add Sleep command support (BSP-780) #719

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feat(lcd): ST7796 Add Sleep command support (BSP-780) #719

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23 changes: 23 additions & 0 deletions components/lcd/esp_lcd_st7796/esp_lcd_st7796_general.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@ static esp_err_t panel_st7796_mirror(esp_lcd_panel_t *panel, bool mirror_x, bool
static esp_err_t panel_st7796_swap_xy(esp_lcd_panel_t *panel, bool swap_axes);
static esp_err_t panel_st7796_set_gap(esp_lcd_panel_t *panel, int x_gap, int y_gap);
static esp_err_t panel_st7796_disp_on_off(esp_lcd_panel_t *panel, bool off);
static esp_err_t panel_st7796_disp_sleep(esp_lcd_panel_t *panel, bool sleep);

typedef struct {
esp_lcd_panel_t base;
Expand Down Expand Up @@ -141,6 +142,8 @@ esp_err_t esp_lcd_new_panel_st7796_general(const esp_lcd_panel_io_handle_t io,
#else
st7796->base.disp_on_off = panel_st7796_disp_on_off;
#endif
st7796->base.disp_sleep = panel_st7796_disp_sleep;
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*ret_panel = &(st7796->base);
ESP_LOGD(TAG, "new st7796 panel @%p", st7796);

Expand Down Expand Up @@ -369,3 +372,23 @@ static esp_err_t panel_st7796_disp_on_off(esp_lcd_panel_t *panel, bool on_off)
ESP_RETURN_ON_ERROR(esp_lcd_panel_io_tx_param(io, command, NULL, 0), TAG, "send command failed");
return ESP_OK;
}

static esp_err_t panel_st7796_disp_sleep(esp_lcd_panel_t *panel, bool sleep)
{
st7796_panel_t *st7796 = __containerof(panel, st7796_panel_t, base);
esp_lcd_panel_io_handle_t io = st7796->io;
int command;

if (sleep) {
command = LCD_CMD_SLPIN;
} else {
command = LCD_CMD_SLPOUT;
}

ESP_RETURN_ON_ERROR(esp_lcd_panel_io_tx_param(io, command, NULL, 0), TAG, "send command failed");
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/* According to the ST7796 datasheet, a delay of at least 120ms is required after sleep in/out commands */
vTaskDelay(pdMS_TO_TICKS(120));

return ESP_OK;
}
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20 changes: 20 additions & 0 deletions components/lcd/esp_lcd_st7796/esp_lcd_st7796_mipi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,7 @@ esp_err_t esp_lcd_new_panel_st7796_mipi(const esp_lcd_panel_io_handle_t io,
panel_handle->mirror = panel_st7796_mirror;
panel_handle->invert_color = panel_st7796_invert_color;
panel_handle->disp_on_off = panel_st7796_disp_on_off;
panel_handle->disp_sleep = panel_st7796_disp_sleep;
panel_handle->user_data = st7796;
*ret_panel = panel_handle;
ESP_LOGD(TAG, "new st7796 panel @%p", st7796);
Expand Down Expand Up @@ -323,4 +324,23 @@ static esp_err_t panel_st7796_disp_on_off(esp_lcd_panel_t *panel, bool on_off)
ESP_RETURN_ON_ERROR(esp_lcd_panel_io_tx_param(io, command, NULL, 0), TAG, "send command failed");
return ESP_OK;
}

static esp_err_t panel_st7796_disp_sleep(esp_lcd_panel_t *panel, bool sleep)
{
st7796_panel_t *st7796 = __containerof(panel, st7796_panel_t, base);
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@cursor cursor bot Feb 2, 2026

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Wrong struct access pattern causes undefined behavior

High Severity

The panel_st7796_disp_sleep function in the MIPI file uses __containerof(panel, st7796_panel_t, base) to access the panel structure, but the MIPI version's st7796_panel_t struct doesn't have a base member. All other functions in this file correctly use (st7796_panel_t *)panel->user_data instead. Using __containerof with a non-existent member will result in undefined behavior and likely memory corruption or crash when the function is called.

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Copilot AI Feb 2, 2026

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Incorrect use of __containerof. The st7796_panel_t struct in this file does not have a 'base' member. The correct way to retrieve the st7796 pointer is: (st7796_panel_t *)panel->user_data, as used in all other functions in this file (see lines 315, 270, 287, 250). The __containerof pattern is only correct in the general variant where st7796_panel_t has 'esp_lcd_panel_t base' as its first member.

Suggested change
st7796_panel_t *st7796 = __containerof(panel, st7796_panel_t, base);
st7796_panel_t *st7796 = (st7796_panel_t *)panel->user_data;

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@espzav espzav Feb 18, 2026

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@AndreaGreco Please, could you apply this suggestion?

esp_lcd_panel_io_handle_t io = st7796->io;
int command;

if (sleep) {
command = LCD_CMD_SLPIN;
} else {
command = LCD_CMD_SLPOUT;
}
ESP_RETURN_ON_ERROR(esp_lcd_panel_io_tx_param(io, command, NULL, 0), TAG, "send command failed");

/* According to the ST7796 datasheet, a delay of at least 120ms is required after sleep in/out commands */
vTaskDelay(pdMS_TO_TICKS(120));
return ESP_OK;
}
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#endif
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