display: Add NO_DISPLAY build config to skip display init

Required for stage 1 loader to allow chainloaded display/dcp experiments
to start with the state left by iboot.

Signed-off-by: Janne Grunau <[email protected]>

Author: jannau

config.h

@@ -12,6 +12,8 @@
 
 // Minimal build for bring-up
 //#define BRINGUP
+// Disable display configuration / bringup on desktop devices
+//#define NO_DISPLAY
 
 // Print RTKit logs to the console
 //#define RTKIT_SYSLOG

src/display.c

@@ -1,5 +1,7 @@
 /* SPDX-License-Identifier: MIT */
 
+#include "../build/build_cfg.h"
+
 #include "display.h"
 #include "adt.h"
 #include "assert.h"
@@ -225,6 +227,11 @@ int display_start_dcp(void)
     if (iboot)
         return 0;
 
+#ifdef NO_DISPLAY
+    printf("display: NO_DISPLAY!\n");
+    return 0;
+#endif
+
     const display_config_t *disp_cfg = &display_config_m1;
 
     if (adt_is_compatible(adt, 0, "J473AP"))
@@ -350,6 +357,11 @@ int display_configure(const char *config)
     dcp_timing_mode_t want;
     struct display_options opts = {0};
 
+#ifdef NO_DISPLAY
+    printf("display: skip configuration (NO_DISPLAY)\n");
+    return 0;
+#endif
+
     display_parse_mode(config, &want, &opts);
 
     u64 start_time = get_ticks();