Re: [PATCH v7 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller

From: Liang Yang
Date: Tue Dec 11 2018 - 04:39:35 EST

Hi Boris,

On 2018/12/11 16:39, Boris Brezillon wrote:
On Tue, 11 Dec 2018 09:56:25 +0800
Liang Yang <liang.yang@xxxxxxxxxxx> wrote:

Hi Miquel,

On 2018/12/10 22:50, Miquel Raynal wrote:
Hi Liang,

Liang Yang <liang.yang@xxxxxxxxxxx> wrote on Mon, 10 Dec 2018 20:12:39
On 2018/12/10 19:38, Boris Brezillon wrote:
On Mon, 10 Dec 2018 19:23:46 +0800
Liang Yang <liang.yang@xxxxxxxxxxx> wrote:
+ mtd->ecc_stats.failed++;
+ continue;
+ }
+ mtd->ecc_stats.corrected += ECC_ERR_CNT(*info);
+ bitflips = max_t(u32, bitflips, ECC_ERR_CNT(*info));
+ }

Are you sure you handle correctly empty pages with bf?
>> if scramble is enable, i would say yes here.
when scramble is disabled, i am considering how to use the helper
nand_check_erased_ecc_chunk, but it seems that i can't get the ecc
bytes which is caculated by ecc the way, nfc dma doesn't send
out the ecc parity bytes.

Even if the ECC engine is disabled?
When ECC engine is disabled, it can read the ecc parity bytes ; but there is another problem that i need to consider how code struct looks better when reading error with ecc opened and then try to raw read.
Is there a good idea?

When reading with ECC enabled, in case of uncorrectable error you
must re-read without ECC, then check if the page is empty or not with
the core helpers (nand_check_erased_*()).

Is this what you meant?
yes. when uncorrectable ECC error, i need firstly read out the ECC bytes
without ECC engine and then use the helper nand_check_erased_ecc_chunk
to check if blank page.
Of course, the precondition is without scrambler, or the bland page can
be detected by meson NFC.

Yep, raw accessors should disable both the scrambler and the ECC
engine (see what's done in sunxi_nand.c).

i see sunxi_nfc_hw_ecc_read_chunk and it will re-read the data for bitflips with scrambler off when ECC failed.
also we can do the same implementation and it seems to be the only answer.