Support of Micron SPI flash (size > 16MB)

Brian Norris computersforpeace at
Thu May 15 23:18:56 PDT 2014

On Fri, May 09, 2014 at 11:44:04AM +0100, Mark Brown wrote:
> On Fri, May 09, 2014 at 10:25:04AM +0000, Mingkai.Hu at wrote:
> > 2.       What are the changes needed for SPI controller to support 4 byte addressing?
> If the SPI controller is a genuine SPI controller and not something
> specially optimised for flash it shouldn't need any changes, it doesn't
> know anything about the data it's sending.

Right. A true SPI controller doesn't need to know anything about
addressing modes.

> The SPI flash code might
> need updating though, I don't know about that.

The SPI flash code in MTD (m25p80.c, some of which is moving to
drivers/mtd/spi-nor/ in -next) already supports 4-byte addressing for
most flash. Check for flash support there.

You might also look at my comments in this commit, regarding the
different types of "4-byte addressing":

commit 87c9511fba2bd069a35e1312587a29e112fc0cd6
Author: Brian Norris <computersforpeace at>
Date:   Thu Apr 11 01:34:57 2013 -0700

    mtd: m25p80: utilize dedicated 4-byte addressing commands

But again, most of this should just work(TM) for true SPI controllers.


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