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SubjectRe: [PATCH] mtd: nand: wait for tWHR after NAND_CMD_STATUS / NAND_CMD_READID
2017-09-26 15:43 GMT+09:00 Boris Brezillon <boris.brezillon@free-electrons.com>:
> On Tue, 26 Sep 2017 12:39:24 +0900
> Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
>
>> Read Status and Read ID require tWHR before reading the first data.
>> Insert a very short wait to make sure to meet the spec.
>>
>> I have not seen any problem report for now, but nand_command() and
>> nand_command_lP() are generic hooks, so it makes sense to implement
>> fail-safe code here.
>>
>> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
>> ---
>


OK, will do.



BTW, I see unconditional wait for tWB a few lines below,
but it gives no performance regression because we will wait
much longer in nand_wait_ready().


/*
* Apply this short delay always to ensure that we do wait tWB in
* any case on any machine.
*/
ndelay(100);

nand_wait_ready(mtd);




--
Best Regards
Masahiro Yamada

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