On Wed, Jul 13, 2016 at 04:20:06PM -0700, Joshua Clayton wrote: > > > On 07/13/2016 01:42 AM, Peter Chen wrote: > > On Wed, Jul 13, 2016 at 09:27:31AM +0200, Philipp Zabel wrote: > >> Am Mittwoch, den 13.07.2016, 10:06 +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 | 53 ++++++++++++++++++++++ > >>> 1 file changed, 53 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..186c58c > >>> --- /dev/null > >>> +++ b/Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt > >>> @@ -0,0 +1,53 @@ > >>> +The generic power sequence library > >>> + > >>> +Some hard-wired USB/MMC devices need to do power sequence to let the > >>> +device work normally, > >> I would replace "to let the device work normally" with "before the > >> device can be enumerated [on the bus]" here. > >> > > Ok. > > > >>> 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 > >> As Joshua pointed out, is this even needed at all? > >> > > If no, how we decide whether allocates pwrseq instance through pwrseq > > library or not? > > > The pwrseq driver is Linux specific. The dts is supposed to be OS agnostic. > It seems to me that If a driver supports pwrseq and the dts elements > are there, it should use them, e.g. if there is a clock, enable the clock. > if there is a reset gpio then take the device into and out of reset during probe. > I agree with you, will delete this property. -- 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
