[PATCH v4 1/6] mtd: spi-nor: Add manufacturer read id function

[Michael Walle]

Hi,

>> > After checking with Macronix designer, a-a-b-b-c-c is the data
>> > arrangement for
>> > read id operation of flash in 8D-8D-8D.
>> 
>> Could you please point to any specification? I doubt there is one
>> and every vendor will do it slightly differently. I mean we already
>> have some flashes which (apparently) reply to RDID in 8d8d8d.
>> 
>> For example, see the Semper flash datasheet:
>> https://www.infineon.com/dgdl/Infineon-S28HS256T_S28HS512T_S28HS01GT_S28HL256T_S28HL512T_S28HL01GT_256-Mb_(32-MB)_512-Mb_(64-MB)_1-Gb_(128-MB)_HS-T_(1.8-V)_HL-T_(3.0-V)_Semper_Flash_with_Octal_Interface-DataSheet-v03_00-EN.pdf?fileId=8ac78c8c7d0d8da4017d0ee6bca96f97&da=t
>> 
>> Have a look at Table 78 (or search for RDIDN_4_0) and Figure 28.
> For Figure 28 in this datasheet, I think it means that data latch
> while DS raising and falling edge.
> The data arrangement of read id follow the 9.2(Manufacturer and Device 
> ID).
> As below are the data arrangement for vendors.
> For Infineon, a-b-c-d-e-f
> For Micron, a-b-c-d-e-f
> For Macronix, a-a-b-b-c-c

So there is no standard among vendors, infineon as well as micron is
using 8d8d8d and macronix is using 8d8d8s. And - please correct me if
I'm wrong - the data strobe signal is optional.

-michael