display: Work around macOS Sonoma firmware bugs

It appears that when macOS is set to non-ProMotion mode, DCP firmware
<14.0 booted from DCP firmware 14.0+ needs a delay before modesetting to
complete the modeset properly.

The cases here are:
- Older m1n1 stage1 will, as far as it's concerned, initialize the
  display properly, but it won't work. It also misses the retina flag,
  since this codepath was intended for external displays. Use the
  missing retina flag as a signal to trigger reconfig.
- If installed as stage1, we reconfigure the display as usual, now with
  the extra delay. We also set the Retina flag now.

The persistence mechanism for the ProMotion flag is unknown. It doesn't
seem to be nvram. It also doesn't matter if we successfully modeset to
120Hz mode and then reboot, it breaks again, so it's not about the
"current" mode sticking.

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

src/display.c

@@ -378,6 +378,9 @@ int display_configure(const char *config)
         return ret;
     }
 
+    // Sonoma bug workaround
+    mdelay(100);
+
     // Find best modes
     dcp_timing_mode_t *tmodes, tbest;
     if ((ret = dcp_ib_get_timing_modes(iboot, &tmodes)) < 0) {
@@ -475,6 +478,7 @@ int display_configure(const char *config)
 
     printf("display: swapped! (swap_id=%d)\n", ret);
 
+    bool reinit = false;
     if (fb_pa != cur_boot_args.video.base || cur_boot_args.video.stride != stride ||
         cur_boot_args.video.width != tbest.width || cur_boot_args.video.height != tbest.height ||
         cur_boot_args.video.depth != 30) {
@@ -483,9 +487,17 @@ int display_configure(const char *config)
         cur_boot_args.video.width = tbest.width;
         cur_boot_args.video.height = tbest.height;
         cur_boot_args.video.depth = 30 | (opts.retina ? FB_DEPTH_FLAG_RETINA : 0);
-        fb_reinit();
+        reinit = true;
+    }
+
+    if (!display_is_external && !(cur_boot_args.video.depth & FB_DEPTH_FLAG_RETINA)) {
+        cur_boot_args.video.depth |= FB_DEPTH_FLAG_RETINA;
+        reinit = true;
     }
 
+    if (reinit)
+        fb_reinit();
+
     /* Update for python / subsequent stages */
     memcpy((void *)boot_args_addr, &cur_boot_args, sizeof(cur_boot_args));
 
@@ -528,6 +540,9 @@ int display_init(void)
     } else if (display_is_external) {
         printf("display: External display found, reconfiguring\n");
         return display_configure(NULL);
+    } else if (!(cur_boot_args.video.depth & FB_DEPTH_FLAG_RETINA)) {
+        printf("display: Internal display with non-retina flag, assuming Sonoma bug and reconfiguring\n");
+        return display_configure(NULL);
     } else {
         printf("display: Display is already initialized (%ldx%ld)\n", cur_boot_args.video.width,
                cur_boot_args.video.height);