On Mon, Dec 05, 2016 at 12:08:32PM +0100, Benjamin Gaignard wrote:
2016-12-05 7:53 GMT+01:00 Thierry Reding thierry.reding@gmail.com:
On Fri, Dec 02, 2016 at 11:17:18AM +0100, Benjamin Gaignard wrote:
Define bindings for pwm-stm32
version 2:
- use parameters instead of compatible of handle the hardware configuration
Signed-off-by: Benjamin Gaignard benjamin.gaignard@st.com
.../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
+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
+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
+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
?
The pwm- prefix is rather redundant since the node is already named pwm. Why not simply st,channels? Or simply channels, since it's not really anything specific to this hardware.
Come to think of it, might be worth having a discussion with our DT gurus about what their stance is on using the # as prefix for numbers (such as in #address-cells or #size-cells). This could be #channels to mark it more explicitly as representing a count.
+- st,32bits-counter: Set if the hardware have a 32 bits counter +- st,complementary: Set if the hardware have complementary output channels
"hardware has" and also maybe mention explicitly that this is a boolean property. Otherwise people might be left wondering what it should be set to. Or maybe word this differently to imply that it's boolean:
- st,32bits-counter: if present, the hardware has a 32 bit counter - st,complementary: if present, the hardware has a complementary output channelI found a way to detect, at probe time, the number of channels, counter size, break input capability and complementary channels so I will remove "st,breakinput", "st,32bits-counter", "st,complementary" and "st,pwm-num-chan" parameters
Oh hey, that's very neat. I suppose in that case my comment above about the break input polarity is somewhat obsoleted. Still I think you won't need two properties. Instead you can follow what other similar properties have done: choose a default (often low-active) and have a single optional property to override the default (often high-active).
In your case:
- st,breakinput-active-high: Some channels have a break input, whose polarity will be active low by default. If this property is present, the channel will be configured with an active high polarity for the break input.
Thierry