[Letux-kernel] [PATCH 0/3] mtd: Ingenic NAND fix for JZ4740

Paul Cercueil paul at crapouillou.net
Sun Nov 7 19:43:33 CET 2021


Hi Nikolaus,

Le dim., nov. 7 2021 at 14:47:43 +0100, H. Nikolaus Schaller 
<hns at goldelico.com> a écrit :
> Hi Paul,
> 
>>  Am 09.10.2021 um 20:49 schrieb Paul Cercueil <paul at crapouillou.net>:
>> 
>>  Hi,
>> 
>>  Looks like NAND support has been broken on the JZ4740 SoC for a 
>> while;
> 
> Yes, I remember someone telling that something was fundamentally 
> broken
> and impossible to be fixed a while ago.

You mean MLC NAND, and that's still broken.

>>  it looks like it comes from the fact that the "hw_oob_first" 
>> mechanism
>>  was dropped from the NAND core and moved to the Davinci driver.
>> 
>>  It turns out the JZ4740 SoC needs it too; I didn't notice it when
>>  writing the new ingenic-nand driver (to replace the old jz4740-nand
>>  driver) most likely because my Device Tree had the "nand-ecc-mode" 
>> set
>>  to "hw_oob_first".
>> 
>>  I am not very sure about patch [1/3]; to me the original code does 
>> not
>>  make sense, and it didn't work out-of-the-box on the JZ4740 without 
>> it.
>>  By applying patch [1/3] the function 
>> nand_read_page_hwecc_oob_first()
>>  can be reused for the JZ4740 SoC as well. But I did not test patch 
>> [1/3]
>>  on Davinci.
> 
> would this also work for jz4780 NAND?

The JZ4780 NAND driver does work, but UBI refuses to use the CI20's 
NAND as it's a MLC.

-Paul




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