Re: [PATCH] ARM: tegra: add "nor-jedec" flash compatible binding

[Brian Norris <computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Fri, May 08, 2015 at 10:00:12AM -0600, Stephen Warren wrote:
> On 05/08/2015 12:21 AM, Rafał Miłecki wrote:
> >Starting with commits
> >8ff16cf ("Documentation: devicetree: m25p80: add "nor-jedec" binding")
> >1103b85 ("mtd: m25p80: bind to "nor-jedec" ID, for auto-detection")
> >we have "nor-jedec" binding indicating support for JEDEC identification.
> 
> The documentation looks quite incomplete. "nor-jedec" sounds like
> it's intended to be something generic. As such, it should be
> documented in e.g.
> Documentation/devicetree/bindings/mtd/nor-jedec.txt, not buried in
> one particular flash device's binding. If it's not intended to be
> generic, why isn't the existing "winbond,w25q32dw" enough?

It is generic, though there are plenty of additional manufacturer/device
pairs that could go on top of it. m25p80 was (one of?) the first
supported, so the naming has been based on legacy, and we're in the
process of unwinding a bit of that. If it helps, we could move the doc
to .../mtd/spi-nor,nor-jedec.txt or something like that.

> Equally, "nor-jedec" doesn't sound like the right name. It doesn't
> differentiate between SPI and parallel NOR flash, which presumably
> need different compatible values, since the programming model is
> quite different, and the compatible value is supposed to
> define/imply the SW-visible programming model.

It's definitely for SPI only. There was much discussion about this a
few months back. Somewhere along the way, it was mentioned that the
context (SPI slave is a child of SPI master) would make this clear. I'm
still not sure why we didn't end up with something more descriptive,
though, like "spi-nor,nor-jedec".

I'm open to change, as this binding is new in 4.1-rc1.

Brian