On Thu, Jul 07, 2016 at 11:47:14AM +0200, Philipp Zabel wrote:
> 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.
>
I agree with you, and will keep property name like last version [1].
--
Best Regards,
Peter Chen
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