Re: [PATCH V2] ARM: tegra: add DT binding for Tegra186 GPIO controllers

[Thierry Reding <thierry.reding@gmail.com>]

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On Fri, Apr 15, 2016 at 10:04:23AM -0600, Stephen Warren wrote:
> On 04/15/2016 03:17 AM, Linus Walleij wrote:
> > On Thu, Apr 14, 2016 at 5:16 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
> > > On 04/14/2016 06:42 AM, Linus Walleij wrote:
> > > > On Tue, Apr 12, 2016 at 7:46 PM, Stephen Warren <swarren@wwwdotorg.org>
> > > > wrote:
> > 
> > > > I suspect that the Tegra definition of a "port" is close to what other
> > > > people
> > > > call a "bank" like I try to define in this patch?
> > > > http://marc.info/?l=linux-gpio&m=145941547420164&w=2
> > > 
> > > There are similarities, but the concepts are quite different. In that
> > > thread, the term "bank" actually refers to an instance of a standalone HW IP
> > > block. Here, "port" is definitely something internal to a single HW block.
> > 
> > OK I get it. I wonder if we can make that common terminology as well.
> > 
> > GPIO bank := unique instance of a common IP block
> > GPIO port := unique line range inside an IP block
> 
> I think this would be hard, and in some places potentially confusing.
> 
> Various HW documentation likely uses the terms bank and port, without regard
> to how those terms are used in documentation for other chips. I'd like the
> binding for any particular chip to use the same terminology as the HW
> documentation for that chip, even if it's inconsistent with other bindings
> (or at least contain an explicit terminology translation table). That's
> because the binding is intended as HW documentation.
> 
> Within the Linux code, we could certainly attempt to use consistent
> terminology. If so, I suggest we use terms that are quite unlikely to be
> used by any HW documentation, or could only realistically be used to mean
> the same thing. If we decided to use "GPIO bank" and "GPIO port" as you
> defined above, yet some HW documentation already used "GPIO bank" to mean a
> subset of GPIOs within a single IP block, and "GPIO port" to mean a single
> GPIO (both of which I think are quite likely/possible), then that's going to
> make matters worse not better.
> 
> Perhaps "HW module"m "IP block" or perhaps "device" would be a reasonable
> term for "GPIO bank" as you defined that above. Of course, bikeshedding:-)
> 
> I'm not sure of a reasonable term for "GPIO port" as you defined it.
> 
> ...
> > It's cool.
> > Acked-by: Linus Walleij <linus.walleij@linaro.org>
> > 
> > I assume you want to merge this through the Tegra tree, or
> > should I apply it to the GPIO tree?
> 
> I'm happy either way. If through the Tegra tree, Thierry would be applying
> it so I'll let him make the call.
> 
> I suspect that both this patch and my earlier "ARM: tegra: fix naming in
> GPIO DT binding header" should be applied through the same tree for
> consistency.

Applied (to the same tree as that other patch), thanks.

Thierry

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