[U-Boot] [patch 2/2] spl: Lightweight UBI and UBI fastmap support

[Tom Rini]

On Sat, Jul 05, 2014 at 09:48:13AM -0000, Thomas Gleixner wrote:

> Booting a payload out of NAND FLASH from the SPL is a crux today, as
> it requires hard partioned FLASH. Not a brilliant idea with the
> reliability of todays NAND FLASH chips.
[snip]
> +		CONFIG_SPL_UBI
> +		Support for a lightweight UBI (fastmap) scanner and
> +		loader

... for the related options, please see doc/README.ubispl

> +Usage notes:
> +
> +In the board config file define for example:
> +
> +#define CONFIG_SPL_UBI
> +#define CONFIG_SPL_UBI_MAX_VOL_LEBS	256
> +#define CONFIG_SPL_UBI_MAX_PEB_SIZE	(256*1024)
> +#define CONFIG_SPL_UBI_MAX_PEBS		4096
> +#define CONFIG_SPL_UBI_VOL_IDS		8
> +
> +The size requirement is roughly as follows:
> +
> +    2k for the basic data structure
> +  + CONFIG_SPL_UBI_VOL_IDS * CONFIG_SPL_UBI_MAX_VOL_LEBS * 8
> +  + CONFIG_SPL_UBI_MAX_PEBS * 64
> +  + CONFIG_SPL_UBI_MAX_PEB_SIZE * UBI_FM_MAX_BLOCKS
> +
> +The last one is big, but I really don't care in that stage. Real world
> +implementations only use the first couple of blocks, but the code
> +handles up to UBI_FM_MAX_BLOCKS.
> +
> +Given the above configuration example the requirement is about 5M
> +which is usually not a problem to reserve in the RAM along with the
> +other areas like the kernel/dts load address.
> +
> +So something like this will do the trick:
> +
> +#define SPL_FINFO_ADDR			0x80800000
> +#define SPL_DTB_LOAD_ADDR		0x81800000
> +#define SPL_KERNEL_LOAD_ADDR		0x82000000
> +
> +In the board file, implement the following:
> +
> +static struct ubispl_load myvolumes[] = {
> +	{
> +		.name		= "Kernel",
> +		.vol_id		= 0,
> +		.load_addr	= (void *)SPL_KERNEL_LOAD_ADDR,
> +	},
> +	{
> +		.name		= "DTB",
> +		.vol_id		= 1,
> +		.load_addr	= (void *)SPL_DTB_LOAD_ADDR,
> +	}
> +};
> +
> +int spl_start_uboot(void)
> +{
> +	struct ubispl_info info;
> +
> +	info.ubi = (struct ubi_scan_info *) SPL_FINFO_ADDR;

OK, so here's some problems with the example.  First, we can / should
(and OK, after you posted the patch this went in) moved stack into DDR
in some cases, so in the case of wanting to use this, DDR would have to
be up in time for that to be a valid option, so we shoudl just do that.
Second, we have CONFIG_SYS_SPL_ARGS_ADDR for where the DT would go and
since Falcon supports uImages only (And if/when zImage is added, we'll
have to sort something out generically) we don't need to hard-code in a
load address for the kernel.

> +	/*
> +	 * Bad block, unrecoverable ECC error, skip the block
> +	 */
> +	if (res) {
> +		ubi_dbg("Skipping bad or unreadable block %d", pnum);

Here and everywhere else, we have debug() please use that.

> +#ifdef CHECKME
> +	/*
> +	 * If fastmap is leaking PEBs (must not happen), raise a
> +	 * fat warning and fall back to scanning mode.
> +	 * We do this here because in ubi_wl_init() it's too late
> +	 * and we cannot fall back to scanning.
> +	 */
> +	if (WARN_ON(count_fastmap_pebs(ai) != ubi->peb_count -
> +		    ai->bad_peb_count - fm->used_blocks))
> +		goto fail_bad;
> +#endif

Use DEBUG here?

> +#ifdef LATER
> +		int image_seq;
> +		ret = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
> +		if (ret && ret != UBI_IO_BITFLIPS) {
> +			ubi_err("unable to read fastmap block# %i EC (PEB: %i)",
> +				i, pnum);
> +			if (ret > 0)
> +				ret = UBI_BAD_FASTMAP;
> +			goto free_hdr;
> +		} else if (ret == UBI_IO_BITFLIPS)
> +			fm->to_be_tortured[i] = 1;
> +
> +		image_seq = be32_to_cpu(ech->image_seq);
> +		if (!ubi->image_seq)
> +			ubi->image_seq = image_seq;
> +		/*
> +		 * Older UBI implementations have image_seq set to zero, so
> +		 * we shouldn't fail if image_seq == 0.
> +		 */
> +		if (image_seq && (image_seq != ubi->image_seq)) {
> +			ubi_err("wrong image seq:%d instead of %d",
> +				be32_to_cpu(ech->image_seq), ubi->image_seq);
> +			ret = UBI_BAD_FASTMAP;
> +			goto free_hdr;
> +		}
> +#endif

What is LATER in this context?  Missing functionality?  Or debug code?

Thanks!

-- 
Tom
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