[U-Boot-Users] Ideas on U-Boot configuration with FDT

[Timur Tabi]

Wolfgang Grandegger wrote:

>> I think fdt_checkboard() (or boardcheck) should be run from inside the 
>> fdt_open_into() command.  This takes advantage of the existing 
>> mechanism of fdt_open_into() to return an error.  It also allows for a 
>> device tree to be opened after U-Boot has booted.
> 
> But it's too late for initial initialization (before RAM is available). 

Just make it so that fdt_open_into() is called early:

	checkboard,
	INIT_FUNC_WATCHDOG_INIT
#if defined(CFG_FDT_ADDR_FLASH)
	init_fdt,
#endif
#if defined(CONFIG_MISC_INIT_F)
	misc_init_f,
#endif
	INIT_FUNC_WATCHDOG_RESET
#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)
	init_func_i2c,
#endif

and init_fdt() calls fdt_open_into().

> Using the FDT directly from ROM is not recommended because access might 
> be slow, but we likely need it for early initialization.

I don't access speed is important for the reading the FDT, especially flash vs. RAM.  It's 
not that much slower.

-- 
Timur Tabi
Linux Kernel Developer @ Freescale