[U-Boot] [PATCH 3/3 V2] ARM: mxs: Fix NAND FCB flashing

[jkrause]

I was wondering about the following warnings while bootings linux 3.15.0-rc5:

[    0.998885] nand: device found, Manufacturer ID: 0x98, Chip ID: 0xd1
[    1.005485] nand: Toshiba NAND 128MiB 3,3V 8-bit
[    1.010165] nand: 128MiB, SLC, page size: 2048, OOB size: 64
[    1.016176] Scanning device for bad blocks
[    1.022444] Bad eraseblock 1 at 0x000000020000
[    1.027444] Bad eraseblock 2 at 0x000000040000
[    1.032612] Bad eraseblock 3 at 0x000000060000

I noticed that these are the FCB pages for the NAND boot. Google found me
this old thread. Nevertheless, I applied the patch on our custom i.MX28
board and the warnings disappeared.

But I still have some questions and remarks:


Marek Vasut-3 wrote
> Fix the method of flashing FCB blocks into NAND. The new env
> writes all four FCB blocks and also does not scrub such a big
> part of the NAND. This fixed complains about busted NAND blocks
> in Linux.
> 
> +	"update_nand_write_fcb="					\
> +		"setenv i ${update_nand_count} ; "			\
> +		"setenv update_nand_offset 0x0 ; "			\
> +		"setexpr update_nand_step "				\
> +			"${update_nand_stride} * ${nand_writesize} ; "	\
> +		"while test ${i} -gt 0 ; do "				\
> +			"echo ${update_nand_offset} ; "			\
> +			"nand scrub -y ${update_nand_offset} "		\
> +				"${nand_erasesize} ; "			\
> +			"nand write.raw ${loadaddr} "			\
> +				"${update_nand_offset} "		\
> +				"${update_nand_stride} ; "		\

Why not just write a page (which contains the FCB) instead of the whole
stride?

There is also a problem about scrubbing of size 128K (which is the erase
size) and writing 128K (which is the size of a search area with 64 pages).
This works for the default settings (fuses not blown) of search stride =
1*64 and search count = 4. But if the fuses is blown and stride = 2*64 and
count = 2 it will scrub 128K and write 256K (size of 128 pages). So the
second half of the search area is not erased before writing.


Marek Vasut-3 wrote
>  	"update_nand_full="		/* Update FCB, DBBT and FW */	\
>  		"if tftp ${update_nand_full_filename} ; then "		\
>  		"run update_nand_get_fcb_size ; "			\
> -		"nand scrub -y 0x0 ${filesize} ; "			\
> -		"nand write.raw ${loadaddr} 0x0 ${fcb_sz} ; "	\
> +		"run update_nand_write_fcb ; "				\
>  		"setexpr update_off ${loadaddr} + ${update_nand_fcb} ; " \
>  		"setexpr update_sz ${filesize} - ${update_nand_fcb} ; " \
>  		"nand write ${update_off} ${update_nand_fcb} ${update_sz} ; " \

Running update_nand_write_fcb erases and writes the FCB search area. The
remaining bytes of the u-boot.nand file are writting before erasing the
corresponding NAND flash bytes. I added something like this before:

 		"setexpr update_off ${loadaddr} + ${update_nand_fcb} ; " \
 		"setexpr update_sz ${filesize} - ${update_nand_fcb} ; " \
 +		"nand erase ${update_nand_fcb} ${update_sz}; " \
 		"nand write ${update_off} ${update_nand_fcb} ${update_sz} ; " \

Is there any reason why this patch is not applied to the u-boot-imx repo?



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