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

Hi Liang,

Liang Yang [off-list ref] wrote on Tue, 11 Dec 2018 09:56:25
+0800:

Hi Miquel,

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

quoted

Hi Liang,

Liang Yang [off-list ref] wrote on Mon, 10 Dec 2018 20:12:39
+0800:
  

quoted

On 2018/12/10 19:38, Boris Brezillon wrote:  

quoted

On Mon, 10 Dec 2018 19:23:46 +0800
Liang Yang [off-list ref] wrote:  
   >>>>>> +			mtd->ecc_stats.failed++;  

quoted

quoted

quoted

+			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 engine.by 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.


Thanks,
Miquèl

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