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    SubjectRe: [PATCH] usb: dwc3: Support the dwc3 host suspend/resume
    Hi Manu,

    On 24 July 2017 at 16:42, Manu Gautam <mgautam@codeaurora.org> wrote:
    > Hi Baolin,
    >
    >
    > On 7/24/2017 11:26 AM, Baolin Wang wrote:
    >
    >>>>> Other than what I pushed in my patch -
    >>>>> ("usb: dwc3: Don't reinitialize core during host bus-suspend/resume")
    >>>>> Just performing pm_request_resume or handling same in dwc3 glue
    >>>>> driver should be sufficient.
    >>>> Yes.
    >>>>
    >>>>> Also, what is trigger for runtime_resume for your platform?
    >>>> In our platform glue layer, we have extcon events to notify there are
    >>>> devices connected, then gule layer will resume dwc3 device.
    >>>>
    >>> IMO you can just perform resume of &dwc->xhci->dev instead of resuming dwc3.
    >>> Since, dwc3 is parent of xhci that will trigger resume of dwc3 as well.
    >> I am not sure this is good enough but it seems can solve some
    >> problems, then we do not need resume/suspend host in dwc3 core.
    >
    > In that case can we proceed with this patch:
    > [1] https://www.spinics.net/lists/linux-usb/msg158682.html
    >
    > For your platform you can pick this patch and resume dwc->xhci->dev resume
    > from your glue driver.
    > Do you have any other concerns?

    The same concern I explained in your patch. If we power off the
    controller when suspend, how can controller work well as host if we do
    not issue dwc3_core_init()? Suppose below cases:
    device attached: resume glue layer (power on dwc3 controller) --->
    resume dwc3 device ---> resume xHCI device
    no device attached: suspend xHCI device ---> suspend dwc3 device --->
    suspend glue layer (we can power off the dwc3 controller now)

    Though now there are no upstreamed glue drivers will power off dwc3
    controller, should we consider this situation?

    --
    Baolin.wang
    Best Regards

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