[h1uke]

Originally Posted by geekmaster

That "factory cable" at your first link is just a homebrew microUSB cable, with the addition of a 1K resistor on the ID pin. Does the PW support that? It would be great if this can be done with such a cable.

u-boot/ imx50_yoshi.c says (CONFIG_BIST, CONFIG_CMD_PMIC and CONFIG_CMD_IDME are defined):

Spoiler:

inline int check_boot_mode(void) 
{
	char boot_mode[20];
	char boot_cmd[20];

#ifdef CONFIG_BIST
	setenv("bootdelay", "-1");
#endif

#if defined(CONFIG_CMD_IDME)
	if (idme_get_var("bootmode", boot_mode, 20)) 
#endif
	{
	    return -1;
	}

	boot_cmd[0] = 0;

	if (!strncmp(boot_mode, "diags", 5)) {
	    printf ("BOOTMODE OVERRIDE: DIAGS\n");
	    strcpy(boot_cmd, "run bootcmd_diags");
	} else if (!strncmp(boot_mode, "fastboot", 8)) {
	    printf ("BOOTMODE OVERRIDE: FASTBOOT\n");
	    strcpy(boot_cmd, "run bootcmd_fastboot");
	} else if (!strncmp(boot_mode, "factory", 7)) {
#if defined(CONFIG_PMIC)
	    if (pmic_charging()) {
		char *cmd = (char *) CONFIG_BISTCMD_LOCATION;		
		/* Ignore any bist commands */
		cmd[0] = 0;

		printf ("BOOTMODE OVERRIDE OVERRIDE: DIAGS\n");

#if defined(CONFIG_CMD_IDME)
		/* Update bootmode idme var */
		idme_update_var("bootmode", "diags");
#endif
		/* Set the bootcmd to diags and boot immediately */
		setenv("bootcmd", "run bootcmd_diags");
		setenv("bootdelay", "0");
		
		return 0;

	    }
#endif	//CONFIG_PMIC
	    printf ("BOOTMODE OVERRIDE: FACTORY\n");
	    strcpy(boot_cmd, "run bootcmd_factory");
	} else if (!strncmp(boot_mode, "reset", 7)) {
	    printf ("BOOTMODE OVERRIDE: RESET\n");
	    strcpy(boot_cmd, "bist reset");
	} else if (!strncmp(boot_mode, "main", 4)) {
	    /* clear bootargs */
	    setenv("bootargs", "\0");

	    /* set bootcmd back to default */
	    sprintf(boot_cmd, "bootm 0x%x", CONFIG_MMC_BOOTFLASH_ADDR);
	    return 0;
	} else {
	    return 0;
	}
	
	setenv("bootcmd", boot_cmd);

	return 0;
}

i.e. the diag mode is forced if pmic_charging() returns nonzero:

Spoiler:

int pmic_charging(void)
{
    int ret;
    unsigned sense_0 = 0;

    /* Detect if a cable is inserted */
    ret = pmic_read_reg(MC34708_REG_INT_SENSE0, &sense_0);
    if (!ret)
	return 0;

    DBG("snse: 0x%x\n\n", sense_0);

    return ((sense_0 & INT0_USBDETS) != 0);
}

and this, in turns, is based in INT0_USBDETS which, according to the datasheet reflects
the voltage applied to the ID pin (#4)

Originally Posted by geekmaster

Some "host mode" adapter cables already have such a jumper. It could be interesting to see if one of those can be used.

as far as I know, the host mode cables have this ID wire grounded.