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    SubjectRe: [PATCH v13 06/12] usb: xhci: use bus->sysdev for DMA configuration
    On Tue, Feb 14, 2017 at 01:58:40PM +0100, Arnd Bergmann wrote:
    > On Tue, Feb 14, 2017 at 1:26 PM, Roger Quadros <rogerq@ti.com> wrote:
    > > On 14/02/17 13:44, Arnd Bergmann wrote:
    > >> On Tue, Feb 14, 2017 at 11:36 AM, Roger Quadros <rogerq@ti.com> wrote:
    >
    > >>> Why are we using sysdev to read DT property? We should be using the
    > >>> XHCI device (&pdev->dev) here, no?
    > >>
    > >> If I remember correctly, this is one of the cases where pdev does not
    > >> have a device node attached to it because it was created by the driver
    > >> of the parent device on the fly in case of dwc3. When you have a pure xhci
    > >> device in DT, the two pointers are the same.
    > >
    > > From drivers/usb/dwc3/host.c
    > >
    > >> if (dwc->usb3_lpm_capable) {
    > >> props[0].name = "usb3-lpm-capable";
    > >> ret = platform_device_add_properties(xhci, props);
    > >> if (ret) {
    > >> dev_err(dwc->dev, "failed to add properties to xHCI\n");
    > >> goto err1;
    > >> }
    > >> }
    > >
    > > So it is setting the usb3-lpm-capable property into the xhci platform device
    > > and we should be reading the property from there.

    Why dwc3 needs another "snps,usb3_lpm_capable"? Why not using
    "usb3-lpm-capable" at firmware directly?

    Peter

    >
    > Hmm, ideally we would only have properties on one of the two, since we
    > refer to the sysdev for the properties regarding DMA and PHY among other
    > things, but I guess that's not an option here, since we can't call
    > platform_device_add_properties() on a dwc_pci device and have to
    > use the xhci pdev instead.
    >
    > Arnd
    >
    --

    Best Regards,
    Peter Chen

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