Re: [PATCH] usb: dwc3: host: inherit dma configuration from parent dev

Felipe Balbi
2016-09-08T09:43:45Z

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Hi,

Arnd Bergmann <arnd@arndb.de> writes:
> On Thursday, September 8, 2016 11:29:04 AM CEST Felipe Balbi wrote:
>> > If we do that, we have to put child devices of the dwc3 devices into
>> > the platform glue, and it also breaks those dwc3 devices that don't
>> > have a parent driver.
>>
>> Well, this is easy to fix:
>>
>> if (dwc->dev->parent) {
>> dwc->sysdev = dwc->dev->parent;
>> } else {
>> dev_info(dwc->dev, "Please provide a glue layer!\n");
>> dwc->sysdev = dwc->dev;
>> }
>
> I don't understand. Do you mean we should have an extra level of
> stacking and splitting "static struct platform_driver dwc3_driver"
> in two so instead of
>
> "qcom,dwc3" -> "snps,dwc3" (usb_bus.sysdev) -> "xhci" (usb_bus.dev)
>
> we do this?
>
> "qcom,dwc3" -> "snps,dwc3" (usb_bus.sysdev) -> "dwc3-glue" -> "xhci" (usb_bus.dev)

no :-)

If we have a parent device, use that as sysdev, otherwise use self as
sysdev.

> That sounds a bit clumsy for the sake of consistency with PCI.
> The advantage is that xhci can always use the grandparent device
> as sysdev whenever it isn't probed through PCI or firmware
> itself, but the purpose of the dwc3-glue is otherwise questionable.
>
> How about adding a 'compatible="snps,dwc3-pci"' property for the dwc3
> device when that is created from the PCI driver and checking for that
> with the device property interface instead? If it's "snps,dwc3"
> we use the device itself while for "snps,dwc3-pci", we use the parent?

Any reason why we wouldn't use e.g. dwc3-omap.dev as sysdev?

--
balbi

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