Re: [PATCH-v3 2/3] mfd: 88pm800: Allow configuration of interrupt clear method

[Vaibhav Hiremath]

On Thursday 25 June 2015 11:02 AM, Krzysztof Kozlowski wrote:
> On 25.06.2015 14:26, Vaibhav Hiremath wrote:
> > On Thursday 25 June 2015 05:33 AM, Krzysztof Kozlowski wrote:
> > > 2015-06-24 18:21 GMT+09:00 Vaibhav Hiremath
> > > <vaibhav.hiremath@xxxxxxxxxx>:
> > > > As per the spec, bit 1 (INT_CLEAR_MODE) of reg addr 0xe
> > > > (page 0) controls the method of clearing interrupt
> > > > status of 88pm800 family of devices;
> > > >
> > > >     0: clear on read
> > > >     1: clear on write
> > > >
> > > > This patch allows to configure this field, through DT.
> > > >
> > > > Also, as suggested by "Lee Jones" renaming DT property and variable
> > > > field to appropriate name.
> > > >
> > > > Signed-off-by: Zhao Ye <zhaoy@xxxxxxxxxxx>
> > > > Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
> > >
> > > It does not look like a property of the board. Instead it looks like a
> > > runtime configuration so it should not be part of DT bindings.
> >
> > Why do you say that?
> >
> > It is very well feature of 88PM860 device, where you can control irq
> > clear operation (either read/write).
> >
> >
> > Thanks,
> > Vaibhav
> >
> > > I understand that previously this was configured by platform data and
> > > now you want to move everything to DT. But this does not belong to
> > > DT...
> >
> > Thats not completely true.
> > I think DT is the right place for this configuration.
>
> DT and its bindings describe the specific board or device. Let me quote:
> <<The "Open Firmware Device Tree", or simply Device Tree (DT), is a data
> structure and language for describing hardware.  More specifically, it
> is a description of hardware that is readable by an operating system...>>
>
> Whether you clear interrupts by writing or reading is configured during
> runtime and it is completely independent to wiring. Each board with
> 88pm800 would allow both methods. So this is not a property of hardware
> in the terms of open firmware. This is a runtime configuration.

Yes,
Fair enough...

I see very little value in runtime configuration, why not just do it
only way (either read or write)?
I would prefer to just set it by default (during init), to clear irq on
write.


Thanks,
Vaibhav
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