Re: [PATCH 3/3] MTD: spi-nor: add flag to not use sector erase.

Michal Suchanek
2015-05-01T07:05:59Z

On 1 May 2015 at 01:13, Marek Vasut <marex@denx.de> wrote:
> On Thursday, April 30, 2015 at 11:13:12 PM, Michal Suchanek wrote:
>> The sector size of the flash memory is unclear from datasheet or may
>> possibly vary between chips so add a flag to always use 4k blocks.
>>
>> Currently 4k blocks are always used when possible but in the future
>> somebody might want to do some optimizations with sector erase.
>>
>> Signed-off-by: Michal Suchanek <hramrach@gmail.com>
>
> I _think_ you might be able to determine the size, no ?
>
> One way is to ask the vendor, but you can also try something like:
> 1) erase the whole SPI NOR
> 2) overwrite it with zeroes (or ones ? I think it should be all ones after
> erasing).
> 3) Erase sector 0
> 4) Read some 128 KiB back
> 5) Observe what is the difference.
>

I can determine it for this particular chip. However, when the vendor
datasheet says the block is 64/32K it might mean that chips with this
ID can have either block size.

It's a value that we don't use anyway so I just mark it as unknown
here for future reference.

Thanks

Michal