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    SubjectRe: [PATCH] usb: dwc3: host: inherit dma configuration from parent dev
    On Wed, Sep 07, 2016 at 05:29:01PM +0800, Peter Chen wrote:
    > On Wed, Sep 07, 2016 at 10:52:46AM +0200, Arnd Bergmann wrote:
    > > On Wednesday, September 7, 2016 3:44:28 PM CEST Peter Chen wrote:
    > > >
    > > > The pre-condition of DT function at USB HCD core works is the host
    > > > controller device has of_node, since it is the root node for USB tree
    > > > described at DT. If the host controller device is not at DT, it needs
    > > > to try to get its of_node, the chipidea driver gets it through its
    > > > parent node [1]
    > >
    > > >
    > > > [1] https://lkml.org/lkml/2016/8/8/119
    > > >
    > >
    > > Ah, this is what I was referring to in the other mail.
    > >
    > > However, the way you set the of_node might be dangerous too:
    > > We should generally not have two platform_device structures with
    > > the same of_node pointer, most importantly it may cause the
    > > child device to be bound to the same driver as the parent
    > > device since the probing is done by compatible string.
    > >
    > > As you tested it successfully, it must work at the moment on your
    > > machine, but it could easily break depending on deferred probing
    > > or module load order.
    > >
    >
    > Currently, I work around above problems by setting core device of_node
    > as NULL at both probe error path and platform driver .remove routine.
    >
    > I admit it is not a good way, but if we only have of_node at device's
    > life periods after probe, it seems ok currently. It is hard to create
    > of_node dynamically when create device, and keep some contents
    > of parent's of_node, and some are not.

    How about turning dwc3 into a library which can be used by a range of
    platform devices? Wouldn't that solve all the current problems, and
    completely avoid the need to copy resources from one platform device
    to another?

    --
    RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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