On Mon, Dec 05, 2016 at 01:12:25PM +0100, Benjamin Gaignard wrote:

2016-12-05 12:23 GMT+01:00 Thierry Reding [off-list ref]:

quoted

On Mon, Dec 05, 2016 at 12:08:32PM +0100, Benjamin Gaignard wrote:

quoted

2016-12-05 7:53 GMT+01:00 Thierry Reding [off-list ref]:

quoted

On Fri, Dec 02, 2016 at 11:17:18AM +0100, Benjamin Gaignard wrote:

quoted

Define bindings for pwm-stm32

version 2:
- use parameters instead of compatible of handle the hardware configuration

Signed-off-by: Benjamin Gaignard <redacted>
---
 .../devicetree/bindings/pwm/pwm-stm32.txt          | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/pwm-stm32.txt

diff --git a/Documentation/devicetree/bindings/pwm/pwm-stm32.txt b/Documentation/devicetree/bindings/pwm/pwm-stm32.txt
new file mode 100644
index 0000000..575b9fb
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/pwm-stm32.txt

@@ -0,0 +1,38 @@
+STMicroelectronics PWM driver bindings for STM32

Technically this bindings describe devices, so "driver binding" is a
somewhat odd wording. Perhaps:

        STMicroelectronics STM32 General Purpose Timer PWM bindings

?

 done

quoted

quoted

+
+Must be a sub-node of STM32 general purpose timer driver
+Parent node properties are describe in ../mfd/stm32-general-purpose-timer.txt

Again, "driver parent node" is odd. Perhaps:

        Must be a sub-node of an STM32 General Purpose Timer device tree
        node. See ../mfd/stm32-general-purpose-timer.txt for details about
        the parent node.

?

done

quoted

quoted

+Required parameters:
+- compatible:                Must be "st,stm32-pwm"
+- pinctrl-names:     Set to "default".
+- pinctrl-0:                 List of phandles pointing to pin configuration nodes
+                     for PWM module.
+                     For Pinctrl properties, please refer to [1].

Your indentation and capitalization are inconsistent. Also, please refer
to the pinctrl bindings by relative path and inline, rather than as a
footnote reference.

OK

quoted

quoted

+
+Optional parameters:
+- st,breakinput:     Set if the hardware have break input capabilities
+- st,breakinput-polarity: Set break input polarity. Default is 0
+                      The value define the active polarity:
+                       - 0 (active LOW)
+                       - 1 (active HIGH)

Could we fold these into a single property? If st,breakinput-polarity is
not present it could simply mean that there is no break input, and if it
is present you don't have to rely on a default.

I need to know if I have to activate breakinput feature and on which level
I will rewrite it like that:
Optional parameters:
- st,breakinput-polarity-high: Set if break input polarity is active
on high level.
- st,breakinput-polarity-high: Set if break input polarity is active
on low level.

How is that different from a single property:

        Optional properties:
        - st,breakinput-polarity: If present, a break input is available
            for the channel. In that case the property value denotes the
            polarity of the break input:
            - 0: active low
            - 1: active high

?

For break input feature I need two information: do I have to active it
and if activated
on which level.
I have two solutions:
- one parameter with a value (0 or 1) -> st,breakinput-polarity
- two parameters without value -> st,breakinput-active-high and
st,breakinput-active-low

By default break input feature is disabled

Right, what I was suggesting is that you use the first solution because
it's the typical way to use for tristate options. It's also much easier
to test for in practice because for the second solution you have to
parse two properties before you know whether it is active or not.

The second is typically the solution for required properties where only
one of the properties is used to override the default.

Thierry
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