Am Donnerstag, den 07.07.2016, 17:14 +0800 schrieb Peter Chen:
> Add binding doc for generic power sequence library.
>
> Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
> ---
> .../bindings/power/pwrseq/pwrseq-generic.txt | 56 ++++++++++++++++++++++
> 1 file changed, 56 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
>
> diff --git a/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt b/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
> new file mode 100644
> index 0000000..4b23834
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
> @@ -0,0 +1,56 @@
> +The generic power sequence library
> +
> +Some hard-wired USB/MMC devices need to do power sequence to let the
> +device work normally, the typical power sequence like: enable USB
> +PHY clock, toggle reset pin, etc. But current Linux USB driver
> +lacks of such code to do it, it may cause some hard-wired USB devices
> +works abnormal or can't be recognized by controller at all. The
> +power sequence will be done before this device can be found at USB
> +bus.
> +
> +The power sequence properties is under the device node.
> +
> +Required properties:
> +- power-sequence: this device needs to do power sequence before enumeration
> +
> +Optional properties:
> +- clocks: the input clock for device.
> +- clock-name: must be "pwrseq-clk"
The "-clk" in the clock name is redundant.
> +- pwrseq-reset-gpios: Should specify the GPIO for reset.
> +- pwrseq-reset-duration-us: the duration in microsecond for assert reset signal.
I understand you want to make it explicit that this GPIO is for the
pwrseq library, but are we really gaining anything over just calling
these reset-gpios and reset-duration-us?
The same applies to the clock name above.
> +Below is the example of USB power sequence properties on USB device
> +nodes which have two level USB hubs.
> +
> +&usbotg1 {
> + vbus-supply = <®_usb_otg1_vbus>;
> + pinctrl-names = "default";
> + pinctrl-0 = <&pinctrl_usb_otg1_id>;
> + status = "okay";
> +
> + #address-cells = <1>;
> + #size-cells = <0>;
> + hub: genesys@1 {
> + compatible = "usb5e3,608";
> + reg = <1>;
> +
> + power-sequence;
> + clocks = <&clks IMX6SX_CLK_CKO>;
> + clock-names = "pwrseq-clk";
> + pwrseq-reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>; /* hub reset pin */
> + pwrseq-reset-duration-us = <10>;
> +
> + #address-cells = <1>;
> + #size-cells = <0>;
> + ethernet: asix@1 {
> + compatible = "usbb95,1708";
> + reg = <1>;
> +
> + power-sequence;
> + clocks = <&clks IMX6SX_CLK_IPG>;
> + clock-names = "pwrseq-clk";
> + pwrseq-reset-gpios = <&gpio4 6 GPIO_ACTIVE_LOW>; /* ethernet_rst */
> + pwrseq-reset-duration-us = <15>;
> + };
This looks weird. The hub and ethernet chips don't have "pwrseq" clock
and reset input pins. I'd remove the clock-names and pwrseq- reset
prefix.
regards
Philipp
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