Re: [PATCH 24/24] mtd: spinand: winbond: Add support for DTR operations

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hello Tudor,

On 11/11/2024 at 14:40:59 GMT, Tudor Ambarus <tudor.ambarus@linaro.org> wrote:

> On 10/25/24 5:15 PM, Miquel Raynal wrote:
>> W25N01JW and W25N02JW support many DTR read modes in single, dual and
>> quad configurations.
>> 
>> DTR modes however cannot be used at 166MHz, as the bus frequency in
>> this case must be lowered to 80MHz.
>
> ha, what's the benefit then? Aren't we better of with non dtr modes
> then? 80 MHz * 2 < 166 MHz?

This is actually a good question, and you are right DDR in this case
does not bring better throughputs, it can even make it a little bit
slower. I think however we should expect some gains at the PCB design
step, which may be way simpler as routing 8 166MHz lines might
apparently be challenging. It is common to have PCB limitations on the
frequency, so enabling DDR can be a great way to keep signal integrity
while definitely improving the performances. However, you're right, I
should probably move these definitions lower in the table to make sure
we run at 166MHz if that's possible.

Thanks,
Miquèl

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