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

From: Liang Yang
Date: Tue Dec 11 2018 - 03:36:41 EST

Hi Miquel,

Thanks for your quickly reply.

On 2018/12/11 15:54, Miquel Raynal wrote:
Hi Liang,

Liang Yang <liang.yang@xxxxxxxxxxx> wrote on Tue, 11 Dec 2018 09:56:25

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?
>> No.
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.

A suppose you meant "blank page"? If yes, then you don't need the
helper to check for only-0xFF pages. If the controller tells you if the
page was blank, then just check for that bit.

i think not. we need to return back the previous problem that how i can get the bitflips of one blank page. i think i need the helper.