On Wed, Aug 21, 2013 at 11:07:42AM +0800, Xiubo Li wrote:
> Signed-off-by: Xiubo Li <Li.Xiubo@xxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/pwm/fsl-ftm-pwm.txt | 52 ++++++++++++++++++++++
> 1 file changed, 52 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt
It used to be that device tree bindings documentation was squashed into
the same commit as the driver. I see some point in splitting this up
given that this will eventually go into a completely separate tree, but
I just want to make sure this is now the official way of splitting
patches so I can tell that to people in good conscience.
> diff --git a/Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt b/Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt
> new file mode 100644
> index 0000000..698965b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/fsl-ftm-pwm.txt
> @@ -0,0 +1,52 @@
> +Freescale FTM PWM controller
> +
> +Required properties:
> +- compatible: should be "fsl,vf610-ftm-pwm"
> +- reg: physical base address and length of the controller's registers
> +- #pwm-cells: Should be 3. Number of cells being used to specify PWM property.
> + First cell specifies the per-chip channel index of the PWM to use, the
> + second cell is the period in nanoseconds and bit 0 in the third cell is
> + used to encode the polarity of PWM output. Set bit 0 of the third in PWM
> + specifier to 1 for inverse polarity & set to 0 for normal polarity.
> +- fsl,pwm-clk-ps: the ftm0 pwm clock's prescaler, divide-by 2^n(n = 0 ~ 7).
> +- fsl,pwm-cpwm: Center-Aligned PWM (CPWM) mode.
> +- fsl,pwm-number: the number of PWM devices, and is must equal to the number
> + of "fsl,pwm-channels".
> +- fsl,pwm-channels: the channels' order which is be used for pwm in ftm0
> + module, and they must be one or some of 0 ~ 7, because the ftm0 only has
> + 8 channels can be used.
> +- for very channel, the revlatived the pinctrl should be at least two state
> + {"enN", "dsN"}, which "en" means "enable", "ds" means "disable" and "N"
> + means the order of the channel.
This is missing a description of the clocks and clock-names properties.
> +
> +Example:
> +
> +pwm0: pwm@40038000 {
> + compatible = "fsl,vf610-ftm-pwm";
> + reg = <0x40038000 0x1000>;
> + #pwm-cells = <3>;
> + pinctrl-names = "en0", "ds0", "en3", "ds3";
> + pinctrl-0 = <&pinctrl_pwm0_ch0_en>;
> + pinctrl-1 = <&pinctrl_pwm0_ch0_ds>;
> + pinctrl-2 = <&pinctrl_pwm0_ch3_en>;
> + pinctrl-3 = <&pinctrl_pwm0_ch3_ds>;
> + fsl,pwm-clk-ps = <7>;
> + fsl,pwm-cpwm = <0>;
> + fsl,pwm-number = <2>;
> + fsl,pwm-channels = <0 3>;
> + ...
And this mixes tabs and spaces for indentation.
> + };
> +
> +leds {
> + compatible = "pwm-leds";
> + led {
> + label = "fsl_led";
> + pwms = <&pwm0 0 10000000 0>;
> + max-brightness = <127>;
> + };
> + backlight {
> + label = "fsl_backlight";
> + pwms = <&pwm0 3 10000000 1>;
> + max-brightness = <100>;
> + };
I don't think I like this at all. This example suggests to use the
pwm-leds driver for backlight control. Why not use pwm-backlight
instead?
Thierry
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