Re: [RFC PATCH 1/5] drivers : introduce device_path api

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On Tue, Nov 27, 2012 at 5:07 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, 26 Nov 2012, Greg KH wrote:
>
>> Ah, here's the root of your problem, right?  You need a way for your
>> hardware to tell the kernel that you have a regulator attached to a
>> specific device?  Using the device path and hard-coding it into the
>> kernel is not the proper way to solve this, sorry.  Use some other
>> unique way to describe the hardware, surely the hardware designers
>> couldn't have been that foolish not to provide this [1]?
>
> As far as I know, the kernel has no other way to describe devices.
>
> What about using partial matches?  In this example, instead of doing a
> wildcard match against
>
>         /platform/usbhs_omap/ehci-omap.0/usb*

IMO, all matches mean the devices are inside the ehci-omap bus, so
the direct/simple way is to enable/disable the regulators in the probe() and
remove() of ehci-omap controller driver.

On the other side, both the two LAN95xx USB devices(hub + ethernet) are
simple self-powered device. Just like other self-powered devices, the power
should be provided from external world, instead of hub driver itself. And it is
doable to power on the devices before creating the specific ehci-omap usb
bus inside ehci-omap driver.

Thanks,
-- 
Ming Lei
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