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Re: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function

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On 29/09/15 18:28, Rob Herring wrote:
> On Tue, Sep 22, 2015 at 12:52 PM, Marc Zyngier <marc.zyngier@arm.com> wrote:
>> of_parse_phandle_with_args() is slightly inflexible as it doesn't
>> allow the (unusual) case where the #*-cells property is not defined.
>> In order to support this, introduce of_parse_phandle_with_opt_args()
>> which assumes that #*-cells is zero when it is not defined,
> 
> zero or cell_count - 1?

Zero is how the lack of #msi-cells property is interpreted. (cell_count
- 1) is how this is implemented.

> I would be okay with always assuming zero rather than being an error
> if that simplifies things. It is not really the kernel's job to be a
> dtb validator.

I'd be fine with that too. I'd just like it to be a defined behaviour,
not an unexpected side effect.

> Also, I assume this was done for some compatibility? In general, we
> should be explicit, so "#msi-cells = <0>" should be recommended and we
> should update dts files if they are not.

I agree that over time, we should update the existing DTS. But I hear
Mark chanting "Stable DT" behind me, so I'm inclined to provide an
transition path... ;-)

I'll respin the series later today.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
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[PATCH 0/4] of: Handle multi-parent version of msi-parent Marc Zyngier <marc.zyngier@arm.com> - 2015-09-22 20:00 +0200
  [PATCH 4/4] irqchip/gic-v3-its: Parse new version of msi-parent property Marc Zyngier <marc.zyngier@arm.com> - 2015-09-22 20:40 +0200
  [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function Marc Zyngier <marc.zyngier@arm.com> - 2015-09-22 20:40 +0200
    Re: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function Rob Herring <robh@kernel.org> - 2015-09-29 19:30 +0200
      Re: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function Marc Zyngier <marc.zyngier@arm.com> - 2015-09-30 11:10 +0200
      Re: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper  function Mark Rutland <mark.rutland@arm.com> - 2015-09-30 16:00 +0200
    Re: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper  function Robin Murphy <robin.murphy@arm.com> - 2015-09-30 17:40 +0200
      Re: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function Marc Zyngier <marc.zyngier@arm.com> - 2015-09-30 19:20 +0200
  [PATCH 2/4] of: irq: Add support for the new definition of "msi-parent" Marc Zyngier <marc.zyngier@arm.com> - 2015-09-22 20:40 +0200
    Re: [PATCH 2/4] of: irq: Add support for the new definition of  "msi-parent" Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-09-23 16:40 +0200
      Re: [PATCH 2/4] of: irq: Add support for the new definition of  "msi-parent" Thomas Gleixner <tglx@linutronix.de> - 2015-09-27 12:40 +0200
        Re: [PATCH 2/4] of: irq: Add support for the new definition of  "msi-parent" Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2015-09-27 15:10 +0200

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