Re: [PATCH RFC V3.5] leds: trigger: Introduce an USB port trigger

[Jacek Anaszewski]

On 08/25/2016 04:30 PM, Alan Stern wrote:
> On Thu, 25 Aug 2016, Jacek Anaszewski wrote:
>
> > I'd see it as follows:
> >
> > #cat available_ports
> > #1-1 1-2 2-1
> >
> > #echo "1-1" > new_port
> >
> > #cat observed_ports
> > #1-1
> >
> > #echo "2-1" > new_port
> >
> > #cat observed_ports
> > #1-1 2-1
> >
> > We've already had few discussions about the sysfs designs trying
> > to break the one-value-per-file rule for LED class device, and
> > there was always strong resistance against.
>
> This scheme has multiple values in both the available_ports and
> observed_ports files.  :-(  Not that I have any better suggestions...

Right, I forgot to add a note here, that this follows space
separated list pattern similarly as in case of triggers attribute.
Of course other suggestions are welcome.

> > > > Also a description of the device connected to the port would be a nice
> > > > feature, however I am not certain about the feasibility thereof.
> > >
> > > What kind of description do you mean? Where should it be used / where
> > > should it appear?
> >
> > Product name/symbol. Actually it should be USB subsystem responsibility
> > to provide the means for querying the product name by port id, if it
> > is possible at all.
>
> 	cat /sys/bus/usb/devices/PORT/product
> 	cat /sys/bus/usb/devices/PORT/manufacturer
>
> These will work if there is a device registered under PORT.

I've found only idProduct and idVendor files. They indeed uniquely
identify the device, but the numbers are not human readable.
Is there a way to retrieve the corresponding names in kernel?
Does the lsusb command do the mapping in the user space or maybe
it takes the names from kernel?

--
Best regards,
Jacek Anaszewski