linux-kernel - Re: [PATCH v2 3/6] dt-bindings: brcmstb-gpio: document properties for wakeup

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Date:	Fri, 29 May 2015 18:51:48 -0700
From:	Gregory Fong <gregory.0xf0@...il.com>
To:	Brian Norris <computersforpeace@...il.com>
Cc:	linux-gpio@...r.kernel.org, Alexandre Courbot <gnurou@...il.com>,
	bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Mark Rutland <mark.rutland@....com>,
	Pawel Moll <pawel.moll@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Russell King <linux@....linux.org.uk>
Subject: Re: [PATCH v2 3/6] dt-bindings: brcmstb-gpio: document properties for wakeup

On Fri, May 29, 2015 at 6:37 PM, Brian Norris
<computersforpeace@...il.com> wrote:
> On Fri, May 29, 2015 at 05:57:50PM -0700, Gregory Fong wrote:
>> On Fri, May 29, 2015 at 5:36 PM, Brian Norris
>> <computersforpeace@...il.com> wrote:
>> > On Thu, May 28, 2015 at 07:14:07PM -0700, Gregory Fong wrote:
>> >> --- a/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt
>> >> +++ b/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt
>> >> @@ -33,6 +33,12 @@ Optional properties:
> ...
>> >>  - #interrupt-cells:
>> >>      Should be <2>.  The first cell is the GPIO number, the second should specify
>> >>      flags.  The following subset of flags is supported:
>> >> @@ -48,7 +54,10 @@ Optional properties:
>> >>      Marks the device node as an interrupt controller
>> >>
>> >>  - interrupt-names:
>> >> -    The name of the IRQ resource used by this controller
>> >> +    The names of the IRQ resources used by this controller
>> >
>> > If you're specifying names, you should list them here.
>>
>> I was wondering about that.  Some bindings have them listed, some
>> don't.  In this case I know what names currently exist but there could
>> certainly be different ones in the future.  How does that work?  Or am
>> I misunderstanding what this field is used for?  Where are the
>> documented rules for this?
>
> The only documentation I see is:
> Documentation/devicetree/bindings/resource-names.txt
>
> That documents the basics of the *-names properties, not their expected
> usage.
>
> In practice, they're only useful if you have enough optional resources
> that fixed indexing isn't sufficient, and you need to use
> platform_get_resource_byname().
>
> So IMO, their purposes seems to be one of these:
> (1) functional (e.g., for get_resource_byname(), when you have more than
>     one optional resource)
> (2) self-documentation (which might run counter to #1, as you begin
>     generating too many unique names)
> (3) no purpose
>
> So IMO, if you ever want (1), they shouldn't have instance-specific
> naming, but should use something generic to the device class. Otherwise,
> they are just self-documentation, and aren't functionally useful. So
> IMO, these sorts of names:
>
>         interrupt-names = "upg_gio_aon", "upg_gio_aon_wakeup";
>
> work better as functional descriptions:
>
>         interrupt-names = "gio", "wakeup";
>
> But in the end, I wouldn't foresee you needing to do (1), so you're left
> with (2) or (3), at which point I'm not sure if you should even mention
> the property.

I'm fine with leaving out the interrupt-names property, since we're
not using it here anyway.  Unless there are serious objections, I'll
plan on remove it from the bindings doc next round.

Thanks,
Gregory
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