Re: [PATCH v5 2/3] Documentation: gpio: Update description for X-Gene standby GPIO controller DTS binding

[Quan Nguyen <qnguyen@apm.com>]

On Fri, Feb 12, 2016 at 9:36 PM, Rob Herring <robh@kernel.org> wrote:
> On Tue, Feb 02, 2016 at 08:46:25AM +0700, Quan Nguyen wrote:
>> On Mon, Feb 1, 2016 at 10:35 PM, Rob Herring <robh@kernel.org> wrote:
>> > On Fri, Jan 29, 2016 at 11:28:54AM +0700, Quan Nguyen wrote:
>> >> Update description for X-Gene standby GPIO controller DTS binding to
>> >> support GPIO line configuration as input, output or external IRQ pin.
>> >>
>> >> Signed-off-by: Y Vo <yvo@apm.com>
>> >> Signed-off-by: Quan Nguyen <qnguyen@apm.com>
>> >> ---
>> >>  .../devicetree/bindings/gpio/gpio-xgene-sb.txt     | 47 ++++++++++++++++++----
>> >>  1 file changed, 40 insertions(+), 7 deletions(-)
>> >>
>> >> diff --git a/Documentation/devicetree/bindings/gpio/gpio-xgene-sb.txt b/Documentation/devicetree/bindings/gpio/gpio-xgene-sb.txt
>> >> index dae1300..7b8b4cb 100644
>> >> --- a/Documentation/devicetree/bindings/gpio/gpio-xgene-sb.txt
>> >> +++ b/Documentation/devicetree/bindings/gpio/gpio-xgene-sb.txt
>> >> @@ -1,10 +1,20 @@
>> >>  APM X-Gene Standby GPIO controller bindings
>> >>
>> >> -This is a gpio controller in the standby domain.
>> >> -
>> >> -There are 20 GPIO pins from 0..21. There is no GPIO_DS14 or GPIO_DS15,
>> >> -only GPIO_DS8..GPIO_DS13 support interrupts. The IRQ mapping
>> >> -is currently 1-to-1 on interrupts 0x28 thru 0x2d.
>> >> +This is a gpio controller in the standby domain. It also supports interrupt in
>> >> +some particular pins which are sourced to its parent interrupt controller
>> >> +as diagram below:
>> >> +                           +-----------------+
>> >> +                           | X-Gene standby  |
>> >> +                           | GPIO controller +--------- GPIO_0
>> >> ++------------+             |                 | ...
>> >> +| Parent IRQ |             |                 +--------- GPIO_8/EXT_INT_0
>> >> +| controller |  EXT_INT_0  |                 | ...
>> >> +| (GICv2)    +-------------+                 +--------- GPIO_[N+8]/EXT_INT_N
>> >> +|            |  ...        |                 |
>> >> +|            |  EXT_INT_N  |                 +--------- GPIO_[N+9]
>> >> +|            +-------------+                 | ...
>> >> +|            |             |                 +--------- GPIO_MAX
>> >> ++------------+             +-----------------+
>> >>
>> >>  Required properties:
>> >>  - compatible: "apm,xgene-gpio-sb" for the X-Gene Standby GPIO controller
>> >> @@ -15,10 +25,18 @@ Required properties:
>> >>               0 = active high
>> >>               1 = active low
>> >>  - gpio-controller: Marks the device node as a GPIO controller.
>> >> -- interrupts: Shall contain exactly 6 interrupts.
>> >> +- interrupts: The EXT_INT_0 parent interrupt resource must be listed first.
>> >> +- interrupt-parent: Phandle of the parent interrupt controller.
>> >> +- interrupt-cells: Should be two.
>> >> +       - first cell is 0-N coresponding for EXT_INT_0 to EXT_INT_N.
>> >> +       - second cell is used to specify flags.
>> >> +- interrupt-controller: Marks the device node as an interrupt controller.
>> >> +- apm,nr-gpios: Optional, specify number of gpios pin.
>> >> +- apm,nr-irqs: Optional, specify number of interrupt pins.
>> >
>> > When is this not 6?
>> >
>> Hi Rob,  by default, this should be 6, but I think this property can
>> help in cases:
>> + Used only 5(or less) first pin as interrupt.
>> + For similar device which has different interrupt pins (8 for example).
>> My idea is to make it a bit more generic by using this optional property.
>
> What is similar device? Another SoC? board? Is 6 fixed in the SoC? I
> think you need more specific compatible string with the SoC name in it
> to determine these setting rather than trying to do something generic.
>

I agree, Rob, compatible string should be suit for other SoC, but I think
we still need this property for case of less than 6 interrupts are needed.

Thanks,
-- Quan Nguyen