On 22.10.18 19:27, Christian Lamparter wrote:
On Monday, October 22, 2018 3:48:29 PM CEST Koen Vandeputte wrote:
On 20.10.18 17:46, Hauke Mehrtens wrote:
On 10/18/2018 02:28 PM, Koen Vandeputte wrote:
starting from upstream commit 577b4eb23811 ("ubi: Reject MLC NAND")
it is not allowed to use UBI and UBIFS on a MLC flavoured NAND flash chip. [1]
According to David Oberhollenzer [2]:
The real problem is that on MLC NAND, pages come in pairs.
Multiple voltage levels inside a single, physical memory cell are used to
encode more than one bit. Instead of just having pages that are twice as big,
the flash exposes them as *two different pages*. Those pages are usually not
ordered sequentially either, but according to a vendor/device specific
pairing scheme.
Within OpenWrt, devices utilizing this type of flash,
combined with ubi(fs) will be bricked when a user upgrades
from 17.01.4 to a newer version as the MLC will be refused.
As these devices are currently advertised as supported by OpenWrt,
we should at least maintain the original state during the lifecycle
of the current releases.
Support can be gracefully ended when a new release-branch is created.
Signed-off-by: Koen Vandeputte <koen.vandepu...@ncentric.com>
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=v4.14.77&id=577b4eb23811dfc8e38924dc476dbc866be74253
[2] https://lore.kernel.org/patchwork/patch/920344/
---
Mainly intended for discussion first on this approach before applying it.
Can be cherrypicked to 18.06.
Feel free to drop your (n)ack on this approach
Have you checked if these are really MLC chips or if they are just
getting detected wrongly?
I think I saw some SPI NAND chips which a patched Linux detected as MLC
but the datasheet said they are SLC chips.
Hauke
Very good point.
I've requested Mikrotik this morning to provide some details about the
actual chips being used since the launch of that board ..
For the RB450/G you can take a look at the User Guide on their side:
<https://mikrotik.com/product/RB450G#fndtn-downloads>
<https://i.mt.lv/cdn/rb_files/rb450GugA.pdf>
On Page 3 there's a "System Board View" with a bottom view of the PCB
and this is where the NAND chip is located. It reads:
HY27UT084G2A
This translates to:
<http://natisbad.org/NAS/refs/Hynix_NAND_flash_part_number_decoding.pdf>
HY27UT084G2A
||||
|||^--- T = MLC + Single Die + Large Block
||^---U = 2.7V~3.6V
|^---7 = NAND FLASH
^---2 = FLASH
So, it is NAND MLC FLASH.
Received a reply from Mikrotik tech dept.:
Hello,
Mainly there are two possible NAND chips for RB450G:
W29N04GVSIAA (see attachment);
MT29F4G08ABADAWPD.
Can you provide some device serial numbers?
Best regards,
Elans L.
Checking the datasheets from both chips mentioned above shows they are both SLC
flash.
@Christian, do you have this board? Could you provide the serial?
Thanks,
Koen
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