feat(fbdev): add docs and allow forcing refresh (#5444)

docs/integration/driver/display/fbdev.rst

@@ -0,0 +1,41 @@
+========================
+Linux Framebuffer Driver
+========================
+
+Overview
+-------------
+
+The Linux framebuffer (fbdev) is a linux subsystem used to display graphics. It is a hardware-independent API that gives user space software
+access to the framebuffer (the part of a computer's video memory containing a current video frame) using only the Linux kernel's own basic
+facilities and its device file system interface, avoiding the need for libraries that implement video drivers in user space. 
+
+Prerequisites
+-------------
+
+Your system has a framebuffer device configured (usually under ``/dev/fb0``).
+
+Configuring the driver
+----------------------
+
+Enable the framebuffer driver support in lv_conf.h, by cmake compiler define or by KConfig. Additionally you may configure the rendering
+mode.
+
+.. code:: c
+
+	#define LV_USE_LINUX_FBDEV           1
+	#define LV_LINUX_FBDEV_RENDER_MODE   LV_DISPLAY_RENDER_MODE_PARTIAL
+
+Usage
+-----
+
+To set up a framebuffer-based display, first create a display with ``lv_linux_fbdev_create``. Afterwards set the framebuffer device
+node on the display (usually this is ``/dev/fb0``).
+
+.. code:: c
+
+	lv_display_t *disp = lv_linux_fbdev_create();
+	lv_linux_fbdev_set_file(disp, "/dev/fb0");
+
+If your screen stays black or only draws partially, you can try enabling direct rendering via ``LV_DISPLAY_RENDER_MODE_DIRECT``. Additionally,
+you can activate a force refresh mode with ``lv_linux_fbdev_set_force_refresh(true)``. This usually has a performance impact though and shouldn't
+be enabled unless really needed.

docs/integration/driver/display/index.rst

@@ -5,7 +5,10 @@ Display
 .. toctree::
     :maxdepth: 2
 
+    fbdev
+    gen_mipi
     ili9341
+    lcd_stm32_hal
     st7735
     st7789
     st7796