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SubjectRe: [PATCH v2 3/6] dt-bindings: brcmstb-gpio: document properties for wakeup
On Fri, May 29, 2015 at 5:36 PM, Brian Norris
<computersforpeace@gmail.com> wrote:
> On Thu, May 28, 2015 at 07:14:07PM -0700, Gregory Fong wrote:
>> Some brcmstb GPIO controllers can be used to wake from suspend, so use the
>> de facto standard property 'wakeup-source' to mark the nodes of controllers
>> with that capability.
>>
>> Also document interrupts-extended, which will be used for wakeup handling
>> because the interrupt parent for the wake IRQ is different from the regular
>> IRQ.
>>
>> Signed-off-by: Gregory Fong <gregory.0xf0@gmail.com>
>> ---
>> New in v2.
>>
>> .../devicetree/bindings/gpio/brcm,brcmstb-gpio.txt | 26 +++++++++++++++++++++-
>> 1 file changed, 25 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt b/Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.txt
>> index 435f1bc..568814f 100644
>> --- 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-parent:
>> phandle of the parent interrupt controller
>>
>> +- interrupts-extended:
>> + Alternate form of specifying interrupts and parents that allows for
>> + multiple parents. This takes precedence over 'interrupts' and
>> + 'interrupt-parent'. This probably must be used if the wakeup-source
>> + property is provided because that may have a different interrupt parent.
>> +
>
> "This probably must be used" seems a little awkward, especially when
> you're just explaining an implementation detail of our SoCs, rather than
> something unique about this binding. Maybe:
>
> "Wakeup-capable GPIO controllers often route their wakeup interrupt
> lines through a different interrupt controller than the primary
> interrupt line, making this property necessary."

That wording does seem better, will change.

>
>> - #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?

>
>> +
>> +- wakeup-source:
>> + GPIOs for this controller can be used as a wakeup source
>>
>> Example:
>> upg_gio: gpio@f040a700 {
>> @@ -63,3 +72,18 @@ Example:
>> interrupt-names = "upg_gio";
>> brcm,gpio-bank-widths = <0x20 0x20 0x20 0x18>;
>> };
>> +
>> + upg_gio_aon: gpio@f04172c0 {
>> + #gpio-cells = <0x2>;
>> + #interrupt-cells = <0x2>;
>
> Might use decimal instead of hex for the above 2 lines?

Sure.

>
>> + compatible = "brcm,bcm7445-gpio", "brcm,brcmstb-gpio";
>> + gpio-controller;
>> + interrupt-controller;
>> + reg = <0xf04172c0 0x40>;
>> + interrupt-parent = <0xc>;
>
> That should be a phandle, not an int (I realize phandles resolve down to
> an integer, but we're speaking DTS, not DTB).

OK.

>
>> + interrupts = <0x6>;
>> + interrupts-extended = <0xc 0x6 0xa 0x5>;
>
> Same here (phandles).
>
> Also, even though the interrupt binding semantics specify precedence
> between interrupts and interrupts-extended, I'd think an example should
> stick to one or the other, no?

This is the output that we actually get from the bootloader. But
regardless, IMO the example should have both cases: precedence is
well-defined, both sets of information are valid, and the driver can
handle the case where interrupts-extended is not an understood
property.

>
>> + interrupt-names = "upg_gio_aon", "upg_gio_aon_wakeup";
>> + wakeup-source;
>> + brcm,gpio-bank-widths = <0x12 0x4>;
>> + };
>
> Reviewed-by: Brian Norris <computersforpeace@gmail.com>

Thanks for the review,
Gregory


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