[U-Boot] environmental "baudrate" not used at boot up

[chrisv at cyberswitching.com]

On Sun, Jan 16, 2011 at 06:01:22AM -0800, chrisv at cyberswitching.com wrote:
> ...
> Any advice on where to take it from here?

Hi everyone,

I investigated this a little further, and I'm wondering if the problem
is related to the initialization ordering in lib_arm/board.c.

Here's the sequence:

   start_armboot():
   1. init_baudrate() -> getenv_r() -> serial_setbrg()
   2. env_relocate()

Note that init_baudrate() calls getenv_r("baudrate") and passes either
the result (on success) or CONFIG_BAUDRATE (on error) to
serial_setbrg().  Only after this does the environment get relocated
using env_relocate().

Based on empirical testing, I've discovered that re-running
init_baudrate() after env_relocate() fixes everything.  The serial
console uses the baud rate stored in the "baudrate" variable now, and
some ordering of display outputs needs to be tweaked so that gibberish
isn't output in the interim.

The attached patch (below) should give a code-centric view.  Please
ignore the minor style changes, as I was hacking code pretty feverishly
to try and figure this out.  To be clear: DO NOT IMPORT THIS CODE
DIRECTLY INTO THE LATEST MASTER!  It will need to be reviewed, tweaked,
and the finally imported by someone who knows more of what they are
doing than I.  :-)

Hope this helps someone else out,

Chris



diff -p -r -U 3 a/drivers/mtd/nand/nand.c b/drivers/mtd/nand/nand.c
--- a/drivers/mtd/nand/nand.c	2009-01-21 14:08:12.000000000 -0800
+++ b/drivers/mtd/nand/nand.c	2011-01-18 21:29:36.000000000 -0800
@@ -57,6 +57,17 @@ static void nand_init_chip(struct mtd_in
 
 }
 
+void display_nand_config(void)
+{
+	int i;
+	unsigned int size = 0;
+	printf("NAND:  ");
+	for (i = 0; i < CONFIG_SYS_MAX_NAND_DEVICE; i++) {
+		size += nand_info[i].size / 1024;
+	}
+	printf("%u MiB\n", size / 1024);
+}
+
 void nand_init(void)
 {
 	int i;
@@ -67,7 +78,6 @@ void nand_init(void)
 		if (nand_curr_device == -1)
 			nand_curr_device = i;
 	}
-	printf("%u MiB\n", size / 1024);
 
 #ifdef CONFIG_SYS_NAND_SELECT_DEVICE
 	/*
diff -p -r -U 3 a/include/nand.h b/include/nand.h
--- a/include/nand.h	2009-01-21 14:08:12.000000000 -0800
+++ b/include/nand.h	2011-01-18 21:29:43.000000000 -0800
@@ -25,6 +25,7 @@
 #define _NAND_H_
 
 extern void nand_init(void);
+extern void display_nand_config(void);
 
 #ifndef CONFIG_NAND_LEGACY
 #include <linux/mtd/compat.h>
diff -p -r -U 3 a/lib_arm/board.c b/lib_arm/board.c
--- a/lib_arm/board.c	2009-01-21 14:08:12.000000000 -0800
+++ b/lib_arm/board.c	2011-01-18 21:29:24.000000000 -0800
@@ -148,10 +148,15 @@ void inline yellow_LED_off(void)__attrib
 static int init_baudrate (void)
 {
 	char tmp[64];	/* long enough for environment variables */
-	int i = getenv_r ("baudrate", tmp, sizeof (tmp));
-	gd->bd->bi_baudrate = gd->baudrate = (i > 0)
-			? (int) simple_strtoul (tmp, NULL, 10)
-			: CONFIG_BAUDRATE;
+	int i;
+	int baudrate = CONFIG_BAUDRATE;
+
+	i = getenv_r ("baudrate", tmp, sizeof (tmp));
+	if (i > 0)
+		baudrate = (int) simple_strtoul(tmp, NULL, 10);
+
+	gd->baudrate = baudrate;
+	gd->bd->bi_baudrate = baudrate;
 
 	return (0);
 }
@@ -256,6 +261,14 @@ init_fnc_t *init_sequence[] = {
 	init_baudrate,		/* initialze baudrate settings */
 	serial_init,		/* serial communications setup */
 	console_init_f,		/* stage 1 init of console */
+#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)
+	init_func_i2c,
+#endif
+	dram_init,		/* configure available RAM banks */
+	NULL,
+};
+
+init_fnc_t *display_sequence[] = {
 	display_banner,		/* say that we are here */
 #if defined(CONFIG_DISPLAY_CPUINFO)
 	print_cpuinfo,		/* display cpu info (and speed) */
@@ -263,10 +276,9 @@ init_fnc_t *init_sequence[] = {
 #if defined(CONFIG_DISPLAY_BOARDINFO)
 	checkboard,		/* display board info */
 #endif
-#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)
-	init_func_i2c,
+#if defined(CONFIG_CMD_NAND)
+	display_nand_config,
 #endif
-	dram_init,		/* configure available RAM banks */
 	display_dram_config,
 	NULL,
 };
@@ -340,7 +352,6 @@ void start_armboot (void)
 	mem_malloc_init (_armboot_start - CONFIG_SYS_MALLOC_LEN);
 
 #if defined(CONFIG_CMD_NAND)
-	puts ("NAND:  ");
 	nand_init();		/* go init the NAND */
 #endif
 
@@ -396,6 +407,18 @@ void start_armboot (void)
 #endif
 	}
 
+	/* Reinitialize the baud rate since the environment wasn't ready */
+	init_baudrate();
+	serial_setbrg();
+	udelay(50000);
+
+	/* Now display the information to the serial console */
+	for (init_fnc_ptr = display_sequence; *init_fnc_ptr; ++init_fnc_ptr) {
+		if ((*init_fnc_ptr)() != 0) {
+			hang ();
+		}
+	}
+
 	devices_init ();	/* get the devices list going. */
 
 #ifdef CONFIG_CMC_PU2