Re: [PATCH 0/2] usb: add HCD providers

[Peter Chen <hzpeterchen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Wed, Jul 13, 2016 at 07:21:09AM +0200, Rafał Miłecki wrote:
> On 13 July 2016 at 06:51, Peter Chen <hzpeterchen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > On Tue, Jul 12, 2016 at 02:35:18PM +0200, Rafał Miłecki wrote:
> >> I was working on an "usbport" LED trigger driver and specifying its
> >> default state in DT. I realized I can't really determine numbering of
> >> USB ports on any device as it depends on compiled drivers and the
> >> loading orders.
> >>
> >> It means that my physical USB port can be e.g. 1-1 or 2-1 depending on
> >> my current config/setup. I needed a way to specify a particular HCD in
> >> DT and then hardcode port number (as this part doesn't change).
> >>
> >
> > I have a question:
> >
> > What does your "usbport" LED trigger for? What kinds of information
> > you would like to show on LED?
> 
> It's a trigger that turns on LED whenever USB device appears at
> specified USB port. There are plenty of home routers that have USB
> labeled LED(s). To support them nicely, first of all we need a trigger
> that will watch for USB subsystem events. Secondly we need a way to
> setup its initial state correctly as most users don't want to play
> with sysfs on their own.
> 
> I sent usbport trigger in:
> [PATCH] leds: trigger: Introduce an USB port trigger
> <1468239883-22695-1-git-send-email-zajec5-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> https://lkml.org/lkml/2016/7/11/305
> You may read commit message and ledtrig-usbport.txt for more details.
> 

Well, it is an interesting use case. You can try to add provider (un)register
at hub driver (drivers/usb/core/hub.c) instead of each platform drivers, you
could refer my USB pwrseq as an example[1].

For roothub, you can get the busnum through comparing controller's of_node, for
internal hub, you can get hub's dev name like (1-1) through comparing
its of_node (you need to describe your hard-wired hub on dts).

http://www.spinics.net/lists/linux-usb/msg143699.html

Two more questions:

- How to support the USB device on the port when boots up?
- Any cases we need to add mapping using new_port_store, the user may
not know bus number for physical port.

-- 

Best Regards,
Peter Chen
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