Re: RFC: prevent auto binding for some platform devices

["Uwe Kleine-König" <Uwe.Kleine-Koenig@digi.com>]

Hello Alexey,

Alexey Zaytsev wrote:
> [Sorry, probably a gmail web-interface bug?]
> 
> On Mon, Jul 21, 2008 at 10:42 AM, Uwe Kleine-König
> <Uwe.Kleine-Koenig@digi.com> wrote:
> > Hello,
> >
> > I have an emedded machine here on my desk and want to stop some
> > driver/device pairs from binding.  There are two types of reason for it:
> >
> >  a) pin muxing doesn't allow attaching e.g. spi and serial at the same
> >     time.  In this case I want a defined "winner" that doesn't depend
> >     on link (or module load) order.
> >
> >  b) the devboard has attached an led on a line that is also available
> >     on a header.  So I don't want to bind the led driver by default
> >     because there might be another device connected to the gpio line.
> >     Still I want to provide the led device and driver such that
> >     userspace can bind these two via sysfs and use it.
> >
> > I think a patch would be easy:
> >
> >  - add a flag to struct device(?) settable by platform code that would
> >    indicate that the device should not autoprobe.
> >
> >  - change bus_attach_device to check that flag and only call
> >    device_attach if it's not set.
> >
> > Would this be sensible?  Would it help anyone else?
> 
> How about simply not registering the missing devices in your
> board setup code?
They are not missing.  In the a) case above they just conflict and I
want to provide a way to change the default from userspace.  E.g.

	echo "serialdevice.1" > /sys/bus/platform/drivers/serialdriver/unbind
	echo "spidevice.1" > /sys/bus/platform/drivers/spidriver/bind

and for b) I want to be able to enable the led if nothing else is
connected to the line.

Best regards
Uwe

-- 
Uwe Kleine-König, Software Engineer
Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany
Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962