Re: [PATCH v3 2/5] mtd: spi-nor: core: Hook manufacture by checking first byte ID

[Michael Walle <mwalle@kernel.org>]

Hi,

>> >> This won't work beacuse the manufacturer id is not always
>> >> one byte long, think of continuation codes. In fact, as the
>> >> flash_info table is of now, we cannot even rely on the
>> >> continuation codes, but we have to always check for the
>> >> complete id_len, i.e. there is at least one hack where
>> >> the id is reversed and the manufacturer is the last byte,
>> >> iirc. some oddball cypress mram chip.
>> > According JEDEC standard, 1st byte is manufacture ID.
>> > I check id table, "cy15x104q" with multi manufacture ID in
>> > later bytes by RDID command(9F).
>> 
>> Yes the currently supported cy15x104q is broken.. but nevertheless
>> it's there. Also some spansion flashes uses winbond manufacturer
>> ids.
> Ok, got it.
> I have a idea, create a member maybe name .check_vendor in 
> spi_nor_manufacturer.
> A example, macronix_check_vendor function for checking this IC whether
> belong macronix or not.
> Each vendor could create their checking function for ID table didn't
> include that ID.
> Is it ok?

Honestly, I'm against adding that vendor discovery stuff to the
generic nor driver. What's the use case of it? You can just
read the ID from userspace and a tool there can decide which
flash it is.

-michael

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