Re: [PATCH 2/2] extcon: gpio: Add dt support for the driver.

[George Cherian]

On 6/17/2014 9:27 PM, Mark Rutland wrote:
> On Tue, Jun 17, 2014 at 04:58:20AM +0100, George Cherian wrote:
> > Add device tree support to extcon-gpio driver.
> > Add devicetree binding documentation
> >
> > Signed-off-by: George Cherian <george.cherian@xxxxxx>
> > ---
> >   .../devicetree/bindings/extcon/extcon-gpio.txt     | 34 ++++++++++++++++++++++
> >   drivers/extcon/extcon-gpio.c                       | 29 ++++++++++++++++++
> >   2 files changed, 63 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/extcon/extcon-gpio.txt
> >
> > diff --git a/Documentation/devicetree/bindings/extcon/extcon-gpio.txt b/Documentation/devicetree/bindings/extcon/extcon-gpio.txt
> > new file mode 100644
> > index 0000000..80b791b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/extcon/extcon-gpio.txt
> > @@ -0,0 +1,34 @@
> > +GPIO based EXTCON
> > +
> > +EXTCON GPIO
> > +-----------
> > +
> > +Required Properties:
> > + - compatible: should be:
> > +   * "ti,extcon-gpio"
> > + - gpios: specifies the gpio pin used.
> > + - debounce: Debounce time for GPIO IRQ in ms
> > + - irq-flags: IRQ flag to be used ( eg: IRQ_TYPE_EDGE_FALLING)
> This looks distinctly odd. Why do you need this here?
The driver takes this as part of platform data. It never continues 
operation if
an invalid irq-flag is supplied. Also these can be used for different SoC's
whose GPIO's might support IRQ_TYPE_EDGE_FALLING/RISING.
Now since this is based on gpio we cant up front give a seperate
"interrupts = " property, since we dont know the gpio-pin irq number.

Chanwoo any comments?
> > +Optional Properties:
> > + - gpio-active-low: Property describing whether gpio active state is 1 or 0
> > +		    If defined , low state of gpio means active.
> Surely this is defined in the gpio flags?

Yes, I will make necessary changes.
> > + - check-on-resume: Property describing whether to check the gpio state
> > +		    while resuming from SLEEP.
> Does this need to be in DT? Surely we could jsut always check this?
okay. For my use-case I dont need this.
Chanwoo, any comments?
> > + - state-on: print_state is overriden with state_on string if provided.
> > +	     If NULL, default method of extcon class is used.
> > + - state_off: print_state is overriden with state_off string  if provided.
> > +	      If NUll, default method of extcon class is used.
> This means nothing from a HW perspective. This describes linux internal
> details.
You mean to say this should not be part of dt?

> [...]
>
> > +		of_property_read_u32(np, "debounce", (u32 *)&pdata->debounce);
> > +		of_property_read_u32(np, "irq-flags", (u32 *)&pdata->irq_flags);
> If you need theses casts, the code is broken.
I dont need this, will remove in v2.
> These functions can only read into a u32. If you pass a smaller type
> you'll trash aribtrary memory locations, and if you pass a larger type
> this is broken for BE.
true.
> Mark.


--
-George

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