Hello,

I just tried to write with "dfu" and dfu-util on the host to a not empty partiton on a nand flash. After the dfu returned without error, I wanted to read the nand partiton with "nand read" and I get ECC errors. This is on an am335x based board (mainline patches coming soon) with ECC BCH8 enabled...

Here is a log:

U-Boot# dfu nand 0 using id 'nand0,0' using id 'nand0,1' using id 'nand0,2' using id 'nand0,3' using id 'nand0,4' using id 'nand0,6' using id 'nand0,7' using id 'nand0,9' GADGET DRIVER: usb_dnl_dfu # DFU complete CRC32: 0x4b157e97 DOWNLOAD ... OK Ctrl+C to exit ... U-Boot# U-Boot# nand read 80100000 780000 2000

NAND read: device 0 offset 0x780000, size 0x2000 ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. ECC: uncorrectable. NAND read from offset 780000 failed -74 0 bytes read: ERROR U-Boot# nand erase.part kernel_b

NAND erase.part: device 0 offset 0x780000, size 0x500000 Erasing at 0xc60000 -- 100% complete. OK U-Boot# dfu nand 0 using id 'nand0,0' using id 'nand0,1' using id 'nand0,2' using id 'nand0,3' using id 'nand0,4' using id 'nand0,6' using id 'nand0,7' using id 'nand0,9' GADGET DRIVER: usb_dnl_dfu # DFU complete CRC32: 0x4b157e97 DOWNLOAD ... OK Ctrl+C to exit ... U-Boot# nand read 80100000 780000 2000

NAND read: device 0 offset 0x780000, size 0x2000 8192 bytes read: OK U-Boot# md 80100000 80100000: 56190527 5657499d 00379251 101f2f00 '..V.IWVQ.7../.. 80100010: 00800080 00800080 f3f41c20 00020205 ........ ....... 80100020: 756e694c 2e332d78 2d302e32 00303172 Linux-3.2.0-r10. 80100030: 00000000 00000000 00000000 00000000 ................ 80100040: e1a00000 e1a00000 e1a00000 e1a00000 ................ 80100050: e1a00000 e1a00000 e1a00000 e1a00000 ................ 80100060: ea000002 016f2818 00000000 002f1f10 .....(o......./. 80100070: e1a07001 e1a08002 e10f2000 e3120003 .p....... ...... 80100080: 1a000001 e3a00017 ef123456 e10f2000 ........V4... .. 80100090: e38220c0 e121f002 00000000 00000000 . ....!......... 801000a0: e59f4784 eb000055 e28f0f4a e8901c4e .G..U...J...N... 801000b0: e590d01c e0400001 e0866000 e08aa000 ......@..`...... 801000c0: e5da9000 e5dae001 e189940e e5dae002 ................ 801000d0: e5daa003 e189980e e1899c0a e08dd000 ................ 801000e0: e28da801 e3a05000 e28aa901 e154000a .....P........T. 801000f0: 2a000016 e084a009 e28f9050 e15a0009 ...*....P.....Z. U-Boot#

Is this a bug or a feature?

If it is a bug, I fixed it as I added in my tree in drivers/mtd/nand/nand_util.c a nand_erase_write_skip_bad() function, which erases before writes to "off, length" ... and call this function in drivers/dfu/dfu_nand.c nand_block_op() instead nand_write_skip_bad() ... Is this a possible solution?

bye, Heiko