DRM¶

Overview¶

The DRM (Direct Rendering Manager) display driver provides support for rendering LVGL directly to Linux framebuffer devices through the DRM/KMS subsystem. It enables running LVGL without a windowing system such as X11 or Wayland, making it suitable for embedded devices, single-board computers, and direct-to-display applications.

The DRM driver interacts directly with the GPU or display controller through /dev/dri/cardX nodes.

Getting Started with DRM¶

Prerequisites¶

The DRM driver requires:

A Linux system with DRM/KMS support enabled in the kernel.
Access to a DRM device node, typically /dev/dri/card0.
Proper permissions to access DRM devices (e.g. running as root or adding the user to the video group).

On Debian/Ubuntu-based systems:

sudo apt-get install libdrm-dev

Configure DRM Driver¶

Enable the DRM driver support in lv_conf.h, by CMake compiler define, or by KConfig:
```
#define LV_USE_LINUX_DRM   1
```
Link against libdrm when building.

Basic Usage¶

#include "lvgl/lvgl.h"
#include "lvgl/demos/lv_demos.h"
#include "lvgl/drivers/drm/lv_linux_drm.h"

int main(void)
{
    /* Initialize LVGL */
    lv_init();

    /* DRM device node */
    const char *device = "/dev/dri/card0";

    /* Create a DRM display */
    lv_display_t *disp = lv_linux_drm_create();

    /* Set DRM device file and connector */
    /* The 2nd argument is the DRM device path */
    /* The 3rd argument is the connector_id (-1 = auto-select first available) */
    lv_linux_drm_set_file(disp, device, -1);

    /* Create demo widgets */
    lv_demo_widgets();

    /* Handle LVGL tasks */
    while (1) {
        uint32_t time_until_next = lv_timer_handler();
        if(time_until_next == LV_NO_TIMER_READY) {
            time_until_next = LV_DEF_REFR_PERIOD;
        }
        lv_delay_ms(time_until_next);
    }

    return 0;
}

Notes¶

connector_id specifies which display output (HDMI, eDP, DP, etc.) should be used. If -1 is passed, the DRM driver will try to automatically pick the first available connector.
DRM requires proper modesetting. By default, LVGL will select a preferred display mode.

Using DRM with GBM¶

The DRM driver can optionally use GBM (Generic Buffer Management) for buffer allocation. This allows the driver to use GPU-friendly buffer objects instead of simple dumb framebuffers.

Enable the following option in your lv_conf.h (or via Kconfig/CMake):

#define LV_USE_LINUX_DRM_GBM_BUFFERS 1

Link against libgbm when building.

When this option is enabled:

Buffers will be allocated using GBM.
This can improve performance and compatibility on platforms where GBM is supported.

Using DRM with EGL¶

The DRM driver can also be combined with EGL for hardware-accelerated rendering via EGL/GLES.

To enable this, set the following options in your lv_conf.h (or via Kconfig/CMake):

#define LV_USE_LINUX_DRM             1
#define LV_USE_LINUX_DRM_GBM_BUFFERS 1
#define LV_LINUX_DRM_USE_EGL         1
#define LV_USE_OPENGLES              1
#define LV_USE_DRAW_OPENGLES         1   /* optional but recommended for performance */

When LV_LINUX_DRM_USE_EGL is enabled, the DRM driver will automatically initialize EGL. No special setup is required beyond the basic DRM initialization shown in Basic Usage.

For a detailed overview of EGL usage and configuration, see EGL.