On Thu, Jul 07, 2016 at 04:53:07PM -0700, Joshua Clayton wrote: > > > On 07/07/2016 02:47 AM, 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. > using reset-gpios makes sense to me too. > The above "power-sequence" might then be better called "reset-on-init", > But really, if a device has a reset gpio shouldn't the default behavior be to > reset it on boot and when coming back from sleep? > Is a special property even needed? The power sequence does not include reset process only, it may include clock and power as well. -- Best Regards, Peter Chen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
