[U-Boot] [PATCH 9/10] board/b4qds:Add support of 2 stage NAND boot-loader

[Prabhakar Kushwaha <prabhakar@freescale.com>]

On 4/2/2014 3:42 AM, Scott Wood wrote:
> On Mon, 2014-03-31 at 15:35 +0530, Prabhakar Kushwaha wrote:
>> +void board_init_f(ulong bootflag)
>> +{
>> +	u32 plat_ratio, sys_clk, uart_clk;
>> +	ccsr_gur_t *gur = (void *)CONFIG_SYS_MPC85xx_GUTS_ADDR;
>> +
>> +	/* Memcpy existing GD at CONFIG_SPL_GD_ADDR */
>> +	memcpy((void *)CONFIG_SPL_GD_ADDR, (void *)gd, sizeof(gd_t));
>> +
>> +	/* Update GD pointer */
>> +	gd = (gd_t *)(CONFIG_SPL_GD_ADDR);
>> +	__asm__ __volatile__("" : : : "memory");
> Explain why this barrier is needed.
>

I followed similar to what is present in arch/powerpc/lib/board.c.
There is is mentioned like
     /* compiler optimization barrier needed for GCC >= 3.4 */
     __asm__ __volatile__("":::"memory");

may i mention this comment here also.


>> +#ifndef CONFIG_SPL_NAND_BOOT
>> +	env_init();
>> +#endif
>> +
>> +	/* relocate environment function pointers etc. */
>> +#ifdef CONFIG_SPL_NAND_BOOT
>> +	nand_spl_load_image(CONFIG_ENV_OFFSET, CONFIG_ENV_SIZE,
>> +			    (uchar *)CONFIG_ENV_ADDR);
>> +	gd->env_addr  = (ulong)(CONFIG_ENV_ADDR);
>> +	gd->env_valid = 1;
>> +#else
>> +	env_relocate();
>> +#endif
> Move env_init() to be just before env_relocate(), rather than
> duplicating the ifdef.

sure, I will do it.

>> +	i2c_init_all();
>> +
>> +	puts("\n\n");
>> +
>> +	gd->ram_size = initdram(0);
> What is the 0?

here  0 is board type.

in arch/powerpc/lib/board.c , we pass it as 0 "dummy arg".
Same I am following here

>> diff --git a/doc/README.b4860qds b/doc/README.b4860qds
>> index 3da77d9..44b46da 100644
>> --- a/doc/README.b4860qds
>> +++ b/doc/README.b4860qds
>> @@ -328,3 +328,38 @@ The below commands apply to both B4860QDS and B4420QDS.
>>      On Linux the interfaces are renamed as:
>>   	. eth2 -> fm1-gb2
>>   	. eth3 -> fm1-gb3
>> +
>> +NAND boot with 2 Stage boot loader
>> +----------------------------------
>> +PBL initialise the internal SRAM and copy SPL(160KB) in SRAM.
>> +SPL further initialise DDR using SPD and environment variables and copy
>> +u-boot(768 KB) from flash to DDR.
>> +Finally SPL transer control to u-boot for futher booting.
>> +
>> +SPL has following features:
>> + - Executes within 256K
>> + - No relocation required
>> +
>> + Run time view of SPL framework :-
>> + -----------------------------------------------
>> + Area        | Address                         |
>> +-----------------------------------------------
>> + Reserve     | 0xFFFC0000 (32KB)               |
> s/Reserve/Reserved/
>
> What is it reserved for/by?  Something external?  Or does U-Boot just
> not use that area currently?  In that case just say "Unused".
Secure boot requires some memory in SRAM in order to put  some headers etc.
May be I mention in README also

>> +NAND Flash memory Map on B4860 and B4420QDS
>> +------------------------------------------
>> + Start		 End		Definition			Size
>> +0x000000	0x0FFFFF	u-boot                          1MB
>> +0x140000	0x15FFFF	u-boot env                      128KB
>> +0x160000	0x17FFFF	FMAN Ucode                      128KB
> What goes at 0x100000?

I think, ENV can start from here.

> What if 0x140000 or 0x160000 is a bad block?
>
>
it can be true for any region. I believe it will be taken care by MTD 
layer to read next good block.

are you suggesting to have a hole of 1 block between every regions.

Regards,
Prabhakar