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@xxxxxxxxx>: > > 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@xxxxxx> > >> --- > >> .../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 channel > > I 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
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