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    SubjectRe: [PATCH] dwc3: gadget: Defer starting the gadget device until gadget is power on
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    Hi Felipe,

    On 13 May 2016 at 20:46, Felipe Balbi <balbi@kernel.org> wrote:
    >
    > Hi,
    >
    > Baolin Wang <baolin.wang@linaro.org> writes:
    >>>>> why does it need restart? Why is dwc3 powered off? Who powers it off?
    >>>>
    >>>> Because when the dwc3 Vbus is off (no cable pluging in now),
    >>>> especially for some mobile device, the system need to power off the
    >>>> dwc3 to save power in this situation.
    >>>
    >>> but dwc3 doesn't do this by itself, so who's doing it?
    >>
    >> Yes, the dwc3 clock is controlled by the Soc system, so the Soc system
    >> can disable the dwc3 clock when there is no cable plugging in.
    >
    > understood.
    >
    >>>>> This looks like a *really* bad power management implementation. Do you
    >>>>> have hibernation enabled? Do you have Clock gating enabled? Which dwc3
    >>>>> version are you using? How was it configured?
    >>>>
    >>>> This is not hibernation, we want to power off the dwc3 to save power
    >>>> when no cable plugging in. Yes, we have clock gating, at this
    >>>> situation we will disable the clock and shutdown the phy to save
    >>>> power. For mobile device, most time no cable plugging in, so we need
    >>>> to think about the power consuming. How do you think this requirement?
    >>>
    >>> Well, seems like you're missing *proper* runtime PM. I've been meaning
    >>> to work on it for weeks, but I still have a few other things to do
    >>> before I get to that. In any case, we don't need to do what you did
    >>> here. There are better ways.
    >>
    >> Make sense.
    >
    > cool, if you wanna work on it, let me know and I can give some details
    > of what I have in mind.

    Could you explain details to me, and I wanna continue to optimize the
    power management things. Thanks.

    >
    > --
    > balbi



    --
    Baolin.wang
    Best Regards

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