Re: [PATCH v1 1/1] mux: mux-intel-usb: Add Intel USB Multiplexer driver

[Hans de Goede]

Hi,

On 31-05-17 17:30, Peter Rosin wrote:
> On 2017-05-31 16:18, Hans de Goede wrote:
> > Hi,
> >
> > On 31-05-17 15:05, Peter Rosin wrote:
> > > On 2017-05-31 14:21, Hans de Goede wrote:
> > > > actually this is the first time I hear about a mux framework
> > > > at all. Is there a git tree with the patches for this somewhere ?
> > >
> > > https://gitlab.com/peda-linux/mux.git in the "mux" branch.
> > >
> > > Series posted here:
> > > https://lkml.org/lkml/2017/5/14/160
> >
> > Thank you.
> >
> > I see that mux_control_get() currently relies on devicetree describing
> > the mux, that is not going to work on non devicetree platforms like
> > x86 where the relation typically is not described ad all (*) ?
>
> Yes, I'm aware of this.

Ok, good.

> I wanted to keep things simple. Also, see
> my reply on the other branch of this discussion.
>
> https://lkml.org/lkml/2017/5/31/58
>
> > Typically there would be a global list of mux_controls maintained
> > by mux_[de]register and then mux_control_get() would walk this list
> > until it finds a matching name. The names to register would then be
> > passed in by platform data/code when registering and likewise the
> > consumer would be passed a unique name to pass into mux_control_get()
> > through platform data / code, would that work for you ?
> >
> > Note one option would be to set the names to use when registering
> > a mux chip through device_properties, this is what the power-supply
> > subsys is currently doing more or less.
>
> I had this lose plan to match by the struct device name, but if that
> is not working the above seems fine too...

There are 2 problems with using dev_name() :

1) dev_name() will be coupled to the mux_chip and one mux_chip may
have multiple controllers (you could add a number postfix to work
around this)

2) The caller of mux_control_get() wants a fixed name, where as
dev_name is not always fixed, e.g. with mux-chips which communicate
via i2c it is something like 7-0064 where 7 is the i2c bus-number
which depends on probe ordering and thus may not even be the same
every boot.

Regards,

Hans