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

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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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