RE: [PATCH 1/1] mtd: spi-nor: everspin: add em004lxb entry

[Flavio Suligoi]

Hi Michael,

..

> Subject: Re: [PATCH 1/1] mtd: spi-nor: everspin: add em004lxb entry
> 
> Hi,
> 
> > Add the Everspin EM0004LXB 4Mb (512KB) Industrial STT-MRAM Persistent
> > Memory.
> 
> Out of curiosity, what is your use case here? Usually, I push back on this small
> MRAM devices in SPI-NOR in favor of the at25 driver. But this datasheet lists
> octal dtr with 200mhz, which seems a bit ridiculous for 512kB. The at25 driver
> only supports single bit SPI of course.
> 
> I'm not sure in which mode you are using this device, though. The DS shows a
> non-volatile configuration register (Table 10, offset 0) and it's default value is
> single bit SPI.
..

We adopted the MRAM to save some important application data in case of
power loss (there are some super-capacitors to maintain the power for a few
seconds).
We use this MRAM in single SPI mode (MISO, MOSI, clock and CS).
About the SPI frequency,  we use only 30MHz, because it is a hw limit of the
MX8MP CPU.

I used the SPI-NOR driver, instead of at25, because in everspin.c there are other
Everspin MRAMs devices (already used in other our boards).

Best regards,
Flavio