Hi Boris,
On 2018-07-19 03:13, Boris Brezillon wrote:
On Wed, 18 Jul 2018 23:23:50 +0200
Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
Boris,
Can you please check the change in qcom_nandc_write_oob() is
valid? I think it is but as this is a bit of a hack I prefer double
checking.
Indeed, it's hack-ish.
Thanks,
Miquèl
Abhishek Sahu <absahu@xxxxxxxxxxxxxx> wrote on Fri, 6 Jul 2018
13:21:56 +0530:
> The NAND base layer calls write_oob() by setting bytes at
> chip->badblockpos with value non 0xFF for updating bad block status.
> The QCOM NAND controller skips the bad block bytes while doing normal
> write with ECC enabled. When initial support for this driver was
> added, the driver specific function was added temporarily for
> block_markbad() with assumption to change for raw read in NAND base
> layer. Moving to raw read for block_markbad() seems to take more time
> so this patch removes driver specific block_markbad() function by
> using following HACK in write_oob() function.
>
> Check for BBM bytes in OOB and accordingly do raw write for updating
> BBM bytes in NAND flash or normal write for updating available OOB
> bytes.
Why don't we change that instead of patching the qcom driver to guess
when the core tries to mark a block bad? If you're afraid of breaking
existing drivers that might rely on the "write/read BBM in non-raw
mode" solution (I'm sure some drivers are), you can always add a new
flag in chip->options (NAND_ACCESS_BBM_IN_RAW_MODE) and only use raw
accessors when this flag is set.
We started with that Only
http://patchwork.ozlabs.org/patch/508565/
and since we didn't conclude, we went for driver
specific bad block check and mark bad block functions.
Now, we wanted to get rid of driver specific functions
1. For bad block check, we found the way to get the BBM bytes
with ECC read. Controller updates BBM in separate register
which we can read and update the same in OOB. Patch #1 of
series does the same.
2. For bad block mark, there is no way to update in ECC mode
that's why we went for HACK to get rid of driver specific
function.
If adding flag is fine now then this HACK won't be required.
Moving to RAW mode for every one still looks risky.
Thanks,
Abhishek
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