Re: [RFC PATCH] [MTD] [OneNAND] Cache Read support

[Adrian Hunter <ext-adrian.hunter@nokia.com>]

ext Kyungmin Park wrote:
>  
>> ext Kyungmin Park wrote:
>>> This patch supports the Cache Read feature in OneNAND.
>>> It's similar with read-while-loading except while read it does sensing the page buffer in NAND
>> core.
>>> So it's called Transfer-While-Sensing. you can find it in OneNAND Spec. in detail.
>>>
>>> Now there's no big performance gain in our test board, Apollon(OMAP2). But others are maybe
>> different.
>>> Any comments are welcome.
>> Cool!
>>
>> Presume you have run the NAND tests
> 
> Sure, it passed NAND tests.
> 
> Could you review the code?

I will try to find some time to look at it maybe this week.

> I wonder why there's no performance gain. It's faster than read-while-loading in the Spec.
> Software overhead? Or there's not many 2 or more pages read?

How are you measuring performance?  I would suggest either dd (if you don't have bad blocks)
or write your own program.

As I see it, unless the read from dataRAM is faster than the sensing/transfer, there won't be
a performance improvement.  So the faster the OneNAND frequency the better.  Ditto bus and
CPU frequencies probably (for memcpy).