[vim3][hdmi] Skip HDMI video output setup in bootloader.

The u-boot display driver may set the hardware to an invalid state
if the display preferred mode is not supported by the driver (for
example, 480x480p @ 60Hz). This caused some display devices to
fail on system boot.

This change fixes the issue by skipping the display layer and
HDMI output module setup in the bootloader, so that the Fuchsia
display driver can configure the display device under a clean state.

Test: On core.vim3 and begonia_eng.vim3.
      (1) Plug the USB power cable of AML028-30MB-A1 to VIM3.
      (2) Power on VIM3.
      (3) Display contents (for core.vim3, it's virtcon; for
          begonia_eng, it's Starnix) show on the panel.
      Manually tested for 20 times on both builds.
Bug: 329337069
Change-Id: I2a37bce4934310fafe6bb5b9a47e4fe874e64d8e
Reviewed-on: https://turquoise-internal-review.googlesource.com/c/third_party/u-boot/+/818490
Reviewed-by: David Pursell <dpursell@google.com>
Reviewed-by: Victor Costan <costan@google.com>
GitOrigin-RevId: fd9c59c143048286803463e84f3c26d997c26403
diff --git a/board/khadas/configs/kvim3.h b/board/khadas/configs/kvim3.h
index 8cd5c92..0a74498 100644
--- a/board/khadas/configs/kvim3.h
+++ b/board/khadas/configs/kvim3.h
@@ -277,7 +277,11 @@
             "else "\
                 "setenv reboot_mode_android ""normal"";"\
                 "if test ${lcd_exist} = 0; then "\
-                    "hdmitx hpd;hdmitx get_preferred_mode;hdmitx get_parse_edid;dovi process;osd open;osd clear;imgread pic logo bootup $loadaddr;bmp display $bootup_offset;bmp scale;vout output ${outputmode};vpp hdrpkt;"\
+                    /* The u-boot display driver may set the hardware to an invalid state if the */\
+                    /* display's preferred display mode is not supported by the driver. Thus, we */\
+                    /* only perform the minimal required initialization steps here and do not    */\
+                    /* set up the video output module on system boot. */\
+                    "hdmitx hpd;hdmitx get_preferred_mode;hdmitx get_parse_edid;"\
                 "else "\
                     "hdmitx hpd;hdmitx get_preferred_mode;hdmitx get_parse_edid;osd dual_logo;vpp hdrpkt;"\