Re: [PATCH v7 5/5] ARM: OMAP: gpmc: add DT bindings for GPMC timings and NAND

[Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>]

* Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org> [121205 15:26]:
> On Wed, 5 Dec 2012 16:33:48 -0600, Jon Hunter <jon-hunter-l0cyMroinI0@public.gmane.org> wrote:
> > On 12/05/2012 04:22 PM, Grant Likely wrote:
> > > 
> > > Please, be specific. Use something like "ti,am3340-gpmc" or
> > > "ti,omap3430-gpmc". The compatible property is a list so that new
> > > devices can claim compatibility with old. Compatible strings that are
> > > overly generic are a pet-peave of mine.
> > 
> > We aim to use the binding for omap2,3,4,5 as well as the am33xx devices
> > (which are omap based). Would it be sufficient to have "ti,omap2-gpmc"
> > implying all omap2+ based devices or should we have a compatible string
> > for each device supported?
> 
> Are they each register-level compatible with one another?
> 
> The general recommended approach here is to make subsequent silicon
> claim compatibility with the first compatible implementation.
> 
> So, for an am3358 board:
> 	compatible = "ti,am3358-gpmc", "ti,omap2420-gpmc";
> 
> Essentially, what this means is that "ti,omap2420-gpmc" is the generic
> value instead of "omap2-gpmc". The reason for this is so that the value
> is anchored against a specific implementation, and not against something
> completely imaginary or idealized. If a newer version isn't quite
> compatible with the omap2420-gpmc, then it can drop the compatible claim
> and the driver really should be told about the new device.

The compatible property can also be used to figure out which ones
need the workarounds in patch #4 of this series for the DT case.
So we should be specific with the compatible.

Regards,

Tony