Hi Jon,
From: Jon Cormier [mailto:jcormier@criticallink.com]
We have a product based on the 335x that has several different models where the only difference is the nand part. We would like to have a unified u-boot that can dynamically configure the nand's ECC, page size, block size, etc using a spi eeprom containing a model number. Both the UBL and u-boot image are stored in nand. We already do this in the kernel. Currently in the UBL all the nand information is setup in #defines during compile time which makes it hard to change at runtime. I am unsure how to go about changing this. Has anyone tried doing this dynamic setup?
(1) For NAND device parameters (like Block-size, Page-size, data-width) These parameter are anyways dynamically determined by reading on chip ONFI page during omap_board_init(). But that's only for u-boot (second-stage). - For SPL these are still #defined based to keep the code-footprint small.
(2) For dynamically selection of ecc-scheme, you need to re-add 'nandecc' command which is kind of deprecated now. Though its driver side support is still present in omap_gpmc.c. - But again, this is not supported for SPL. If everyone agrees, we should add this to main NAND framework instead of cluttering individual board-files. ------------------------------------------------------------------ File: arch/arm/cpu/armv7/omap3/board.c
#if defined(CONFIG_NAND_OMAP_GPMC) & !defined(CONFIG_SPL_BUILD) /****************************************************************************** * OMAP3 specific command to switch between NAND HW and SW ecc *****************************************************************************/ static int do_switch_ecc(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { if (argc < 2 || argc > 3) goto usage;
if (strncmp(argv[1], "hw", 2) == 0) { if (argc == 2) { omap_nand_switch_ecc(1, 1); } else { if (strncmp(argv[2], "hamming", 7) == 0) omap_nand_switch_ecc(1, 1); else if (strncmp(argv[2], "bch8", 4) == 0) omap_nand_switch_ecc(1, 8); else goto usage; } } else if (strncmp(argv[1], "sw", 2) == 0) { omap_nand_switch_ecc(0, 0); } else { goto usage; }
return 0;
usage: printf ("Usage: nandecc %s\n", cmdtp->usage); return 1; }
U_BOOT_CMD( nandecc, 3, 1, do_switch_ecc, "switch OMAP3 NAND ECC calculation algorithm", "hw [hamming|bch8] - Switch between NAND hardware 1-bit hamming and" " 8-bit BCH\n" " ecc calculation (second parameter may" " be omitted).\n" "nandecc sw - Switch to NAND software ecc algorithm." );
#endif /* CONFIG_NAND_OMAP_GPMC & !CONFIG_SPL_BUILD */ ------------------------------------------------------------------
(3) If you need to have generic SPL too, then you might need to try NANDI2C boot-mode of AM335x. (please refer AM335x TRM).
We are currently based off of the 2013.10 tag but will move forward if needed.
Yes, I would suggest to move to latest u-boot which has support for BCH16 ecc-scheme, as higher ecc-scheme work better with newer technology NAND and MLC NAND devices which are more prone to bit-flips.
with regards, pekon
-- Jonathan Cormier CriticalLink