Fix EXAR debug port issue on MTCDT, which caused boot hangs

3 files changed, 46 insertions, 2 deletions

diff --git a/recipes-bsp/u-boot/u-boot-2016.09.01/mtcdt_flush_console_autoboot.patch b/recipes-bsp/u-boot/u-boot-2016.09.01/mtcdt_flush_console_autoboot.patch
new file mode 100644
index 0000000..d08843a
--- /dev/null
+++ b/recipes-bsp/u-boot/u-boot-2016.09.01/mtcdt_flush_console_autoboot.patch
@@ -0,0 +1,43 @@
+# This change sets the bootdelay to 2 seconds.  On old devices
+# the bootdelay may be in the environment variable partitions.
+# When updating a system, u-boot setenv command must be used
+# to set the bootdelay to 2 in the environment.  A bootdelay
+# of zero will make it nearly impossible to enter U-Boot,
+# and zero is the old default, and may be in the environment.
+# For MTCDT only the unpowered EXAR serial to USB convertor
+# leaks the output of the console back to the input in some
+# cases.  Therefore it is necessary to flush the UART before
+# attempting to monitor keystrokes.  The output of the
+# console must be quiet, or in the case of the normal
+# boot where the EXAR part is unpowered, the read of the
+# keyboard may be reading output to the console screen.
+# This problem never occurs if the EXAR part is connected
+# to a PC, and is powered.
+diff -Naru orig/common/autoboot.c new/common/autoboot.c
+--- orig/common/autoboot.c	2019-08-15 10:56:58.183468370 -0500
++++ new/common/autoboot.c	2019-08-15 10:30:11.363515940 -0500
+@@ -219,6 +219,12 @@
+ 	printf("Hit any key to stop autoboot: %2d ", bootdelay);
+ #endif
+ 
++        /* Flush input -- must be done because of loopback
++         * issue on MTCDT models with unpowered EXAR part
++         * which do loopback unintentionally by default.
++         */
++        while (tstc())
++                getc();
+ 	/*
+ 	 * Check if key already pressed
+ 	 */
+diff -Naru orig/configs/at91sam9x5ek_nandflash_defconfig new/configs/at91sam9x5ek_nandflash_defconfig
+--- orig/configs/at91sam9x5ek_nandflash_defconfig	2019-08-15 10:49:30.223481632 -0500
++++ new/configs/at91sam9x5ek_nandflash_defconfig	2019-08-15 10:50:10.703480433 -0500
+@@ -3,7 +3,7 @@
+ CONFIG_TARGET_AT91SAM9X5EK=y
+ CONFIG_SPL=n
+ CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9X5,SYS_USE_NANDFLASH"
+-CONFIG_BOOTDELAY=0
++CONFIG_BOOTDELAY=2
+ CONFIG_HUSH_PARSER=y
+ CONFIG_SYS_PROMPT="U-Boot> "
+ CONFIG_CMD_BOOTZ=y
diff --git a/recipes-bsp/u-boot/u-boot.inc b/recipes-bsp/u-boot/u-boot.inc
index 56265ff..8854181 100644
--- a/recipes-bsp/u-boot/u-boot.inc
+++ b/recipes-bsp/u-boot/u-boot.inc
@@ -4,7 +4,7 @@ SECTION = "bootloaders"
 PROVIDES = "virtual/bootloader"
 
 # New U-Boot with suppressed version.
-PR="m2"
+PR="m3"
 
 LICENSE = "GPLv2+"
 LIC_FILES_CHKSUM = "file://Licenses/README;md5=a2c678cfd4a4d97135585cad908541c6"
diff --git a/recipes-bsp/u-boot/u-boot_2016.09.01.bb b/recipes-bsp/u-boot/u-boot_2016.09.01.bb
index d94ba56..3771ee1 100644
--- a/recipes-bsp/u-boot/u-boot_2016.09.01.bb
+++ b/recipes-bsp/u-boot/u-boot_2016.09.01.bb
@@ -14,7 +14,8 @@ SRC_URI = "ftp://ftp.denx.de/pub/u-boot/u-boot-${PV}.tar.bz2 \
            file://hide_uboot_version.patch"
 
 SRC_URI_append_mtcdt = " \
-           file://mtcdt.patch"
+           file://mtcdt.patch \
+           file://mtcdt_flush_console_autoboot.patch"
 
 SRC_URI_append_mtcap = " \
            file://mtcdt.patch"