drivers: display: sdl: Ensure task thread is run once on init

Adds taking of the task semaphore after creating the display thread
to ensure that the thread is run once, executing the SDL init.
Adjust the threads priority to match the main thread.

Signed-off-by: Fabian Blatz <[email protected]>

Author: faxe1008

drivers/display/Kconfig.sdl

@@ -90,7 +90,7 @@ config SDL_DISPLAY_TRANSPARENCY_GRID_CELL_COLOR_2
 
 config SDL_DISPLAY_THREAD_PRIORITY
 	int "SDL display thread priority"
-	default NUM_PREEMPT_PRIORITIES
+	default MAIN_THREAD_PRIORITY
 	help
 	  Drawing thread priority.
 

drivers/display/display_sdl.c

@@ -125,6 +125,8 @@ static void sdl_task_thread(void *p1, void *p2, void *p3)
 					 CONFIG_SDL_DISPLAY_TRANSPARENCY_GRID_CELL_COLOR_2,
 					 CONFIG_SDL_DISPLAY_TRANSPARENCY_GRID_CELL_SIZE);
 
+	k_sem_give(&disp_data->task_sem);
+
 	if (rc != 0) {
 		nsi_print_error_and_exit("Failed to create SDL display");
 		return;
@@ -169,6 +171,8 @@ static int sdl_display_init(const struct device *dev)
 			K_KERNEL_STACK_SIZEOF(disp_data->sdl_thread_stack),
 			sdl_task_thread, (void *)dev, NULL, NULL,
 			CONFIG_SDL_DISPLAY_THREAD_PRIORITY, 0, K_NO_WAIT);
+	/* Ensure task thread has performed the init */
+	k_sem_take(&disp_data->task_sem, K_FOREVER);
 
 	return 0;
 }