Linux modified the MTD driver interface in commit edbc4540 (with the
same name as this commit). The effect is that calls to mtd_read will
not return -EUCLEAN if the number of ECC-corrected bit errors is below
a certain threshold, which defaults to the strength of the ECC. This
allows -EUCLEAN to stop indicating "some bits were corrected" and begin
indicating "a large number of bits were corrected, the data held in
this region of flash may be lost soon". UBI makes use of this and when
-EUCLEAN is returned from mtd_read it will move data to another block
of flash. Without adopting this interface change UBI on U-boot attempts
to move data between blocks every time a single bit is corrected using
the ECC, which is a very common occurance on some devices.
For some devices where bit errors are common enough, UBI can get stuck
constantly moving data around because each block it attempts to use has
a single bit error. This condition is hit when wear_leveling_worker
attempts to move data from one PEB to another in response to an
-EUCLEAN/UBI_IO_BITFLIPS error. When this happens ubi_eba_copy_leb is
called to perform the data copy, and after the data is written it is
read back to check its validity. If that read returns UBI_IO_BITFLIPS
(in response to an MTD -EUCLEAN) then ubi_eba_copy_leb returns 1 to
wear_leveling worker, which then proceeds to schedule the destination
PEB for erasure. This leads to erase_worker running on the PEB, and
following a successful erase wear_leveling_worker is called which
begins this whole cycle all over again. The end result is that (without
UBI debug output enabled) the boot appears to simply hang whilst in
reality U-boot busily works away at destroying a block of the NAND
flash. Debug output from this situation:
UBI DBG: ensure_wear_leveling: schedule scrubbing
UBI DBG: wear_leveling_worker: scrub PEB 1027 to PEB 4083
UBI DBG: ubi_io_read_vid_hdr: read VID header from PEB 1027
UBI DBG: ubi_io_read: read 4096 bytes from PEB 1027:4096
UBI DBG: ubi_eba_copy_leb: copy LEB 0:0, PEB 1027 to PEB 4083
UBI DBG: ubi_eba_copy_leb: read 1040384 bytes of data
UBI DBG: ubi_io_read: read 1040384 bytes from PEB 1027:8192
UBI: fixable bit-flip detected at PEB 1027
UBI DBG: ubi_io_write_vid_hdr: write VID header to PEB 4083
UBI DBG: ubi_io_write: write 4096 bytes to PEB 4083:4096
UBI DBG: ubi_io_read_vid_hdr: read VID header from PEB 4083
UBI DBG: ubi_io_read: read 4096 bytes from PEB 4083:4096
UBI DBG: ubi_io_write: write 4096 bytes to PEB 4083:8192
UBI DBG: ubi_io_read: read 4096 bytes from PEB 4083:8192
UBI: fixable bit-flip detected at PEB 4083
UBI DBG: schedule_erase: schedule erasure of PEB 4083, EC 55, torture 0
UBI DBG: erase_worker: erase PEB 4083 EC 55
UBI DBG: sync_erase: erase PEB 4083, old EC 55
UBI DBG: do_sync_erase: erase PEB 4083
UBI DBG: sync_erase: erased PEB 4083, new EC 56
UBI DBG: ubi_io_write_ec_hdr: write EC header to PEB 4083
UBI DBG: ubi_io_write: write 4096 bytes to PEB 4083:0
UBI DBG: ensure_wear_leveling: schedule scrubbing
UBI DBG: wear_leveling_worker: scrub PEB 1027 to PEB 4083
...
This patch adopts the interface change as in Linux commit edbc4540 in
order to avoid such situations. Given that none of the drivers under
drivers/mtd return -EUCLEAN, this should only affect those using
software ECC. I have tested that it works on a board which is
currently out of tree, but which I hope to be able to begin
upstreaming soon.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Acked-by: Stefan Roese <sr@denx.de>
This patch is essentially an update of u-boot MTD subsystem to
the state of Linux-3.7.1 with exclusion of some bits:
- the update is concentrated on NAND, no onenand or CFI/NOR/SPI
flashes interfaces are updated EXCEPT for API changes.
- new large NAND chips support is there, though some updates
have got in Linux-3.8.-rc1, (which will follow on top of this patch).
To produce this update I used tag v3.7.1 of linux-stable repository.
The update was made using application of relevant patches,
with changes relevant to U-Boot-only stuff sticked together
to keep bisectability. Then all changes were grouped together
to this patch.
Signed-off-by: Sergey Lapin <slapin@ossfans.org>
[scottwood@freescale.com: some eccstrength and build fixes]
Signed-off-by: Scott Wood <scottwood@freescale.com>
Consolidate some code in mtd_get_len_incl_bad(), and fix a condition
where a valid partition could be reported as truncated if it has a
good block at the end of the device (unlikely, since the BBT is usually
there).
Fix mid-block declarations in net_part_size().
Signed-off-by: Scott Wood <scottwood@freescale.com>
Reviewed-by: Ben Gardiner <bengardiner@nanometrics.ca>
The logic to 'spread' mtd partitions needs to calculate the length in
the mtd device, including bad blocks.
This patch introduces a new function, mtd_get_len_incl_bad that can
return both the length including bad blocks and whether that length
was truncated on the device. This new function will be used by the
mtdparts spread command later in this series. The definition of the
function is #ifdef'd out in configurations that do not use the new
'mtdparts spread' command.
Signed-off-by: Ben Gardiner<bengardiner@nanometrics.ca>
CC: Scott Wood <scottwood@freescale.com>
Remove a printf() from add_mtd_device(), which produces spurious output.
Signed-off-by: Piotr Ziecik <kosmo@semihalf.com>
Signed-off-by: Stefan Roese <sr@denx.de>
This MTD part infrastructure will be used by the upcoming
UBI support.
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Stefan Roese <sr@denx.de>
Wolfgang Denk
Paul Burton
Sergey Lapin
Mike Frysinger
Scott Wood
Ben Gardiner
Piotr Ziecik
Kyungmin Park