[PATCH v2 3/3] mtd: spi-nor: fujitsu: Add support for MB85RS4MTY chip

Ronan Dalton Ronan.Dalton at alliedtelesis.co.nz
Wed Jul 1 16:48:21 PDT 2026


Hi Michael,

On Wed, 2026-07-01 at 10:05 +0200, Michael Walle wrote:
> Hi,
> 
> On Fri Jun 26, 2026 at 4:21 AM CEST, Ronan Dalton wrote:
> > The MB85RS4MTY chip is similar to the MB85RS1MT chip, but it has a
> > higher capacity and can handle higher temperatures. Compared to the
> > MB85RS1MT chip, this chip has an expanded set of opcodes which
> > allow
> > control over power-saving modes, access to a special sector data
> > area,
> > and reading of the unique ID and serial number. However, since the
> > spi-nor subsystem doesn't support these extended abilities, they
> > are not
> > taken advantage of here.
> 
> I'm sorry, but we don't accept any new parts, which clearly emulates
> an EEPROM and has no concept of erase blocks (or don't even emulate
> the erase opcode). I understand, that it was very convenient to have
> a block device. But I want to move away from that NO_ERASE hack and
> having two different drivers for the same hardware device.
> 
> Maybe someone in the loop has an idea how to move forward regarding
> the filesystem issue.
> 
> ..
> 
> > +	}, {
> > +		.id = SNOR_ID(0x04, 0x7f, 0x49),
> > +		.name = "mb85rs4mty",
> 
> We dropped adding names of the flashes for new parts, because of
> notorious id reuse.
> 
> -michael
> 
> > +		.size = SZ_512K,
> > +		.sector_size = SZ_512K,
> > +		.flags = SPI_NOR_NO_ERASE
> >  	}
> >  };
> >  

Thanks for your feedback. Based on this I will not move forward with
this patchset, at least in its current form.

Regards,
Ronan.


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