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

[Stephen Warren <swarren@wwwdotorg.org>]

On 05/08/2015 02:57 PM, Geert Uytterhoeven wrote:
> On Fri, May 8, 2015 at 8:43 PM, Brian Norris
> <computersforpeace@gmail.com> wrote:
>> 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".
>
> What about "jedec,spi-nor"?

That seems unique enough to me, or the options below if they're actually 
applicable.

> Is this "SERIAL FLASH DISCOVERABLE PARAMETERS (SFDP)"?
> https://www.jedec.org/standards-documents/docs/jesd216b
> (Don't have time to register with jedec now...)
>
> If yes, "jedec,sfdp"? "jedec,jesd216b"?