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    SubjectRe: [PATCH 2/3] usb: aspeed-vhub: support remote wakeup feature
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    On Thu, 2021-12-02 at 03:03 +0000, Neal Liu wrote:
    > >
    > Let's me describe more details for our hardware behavior and hope you
    > understand.
    >
    > HUB00[3]: MANUAL_REMOTE_WAKEUP
    > HUB00[4]: AUTO_REMOTE_WAKEUP
    >
    > Set HUB00[3] implies USB device will do remote wakeup if any write
    > command to vhub register.
    > Set HUB00[4] implies USB device will do remote wakeup. It can only be
    > set in suspend state.
    >
    > For current design, d->wakeup_en only controls whether HUB00[4] can
    > be set through usb_gadget_ops.wakeup().
    > If some applications (take KVM as example) want to wakeup host by
    > sending a packet, it won't go through sb_gadget_ops.wakeup().
    > We enable HUB00[3] to fix this problem. It won't override above
    > mentioned behavior.
    > If host has enabled the USB_DEVICE_REMOTE_WAKEUP feature, it has 2
    > ways to wakeup host.
    > 1. set srp 1 (/sys/device/platform/xxxxxxxxx/udc/xxxxxx/srp)
    > 2. emulated device has activity
    > If host has disabled the USB_DEVICE_REMOTE_WAKEUP feature, these 2
    > ways still cannot wakeup host even if USB bus is in resume state.
    > Thanks

    So what you are saying is that currently, the various gadgets aren't
    calling usb_gadget_wakeup() ?

    Ie. it should be a gadget policy to decide when to wake-up I suppose,
    but it's true that nothing in the core nor the existing gadgets seem to
    handle that.

    I think what you propose is a band-aid. The real problem is that the
    gadget drivers should trigger wakeups (or the core should do so on
    activity).

    That said, for now, I don't object to adding that "auto" bit, but I
    would prefer if that behaviour was use configurable.

    Cheers,
    Ben.

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