Re: [PATCH v2 0/3] device tree spidev solution - driver_override for SPI

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Jan,

On Wed, Mar 6, 2019 at 2:01 PM Jan Kundrát <jan.kundrat@xxxxxxxxx> wrote:
> On úterý 5. března 2019 19:39:03 CET, Trent Piepho wrote:
> > On Tue, 2019-03-05 at 12:15 +0100, Jan Kundrát wrote:
> >> On čtvrtek 20. září 2018 21:18:27 CEST, Trent Piepho wrote: ...
> >
> > The first and last are in, 5039563e7c25 and 605b3bec73cb.  The second
> > isn't.  It's not strictly necessary to use it.  But it does make the
> > udev rules a lot smaller and I think makes the system easier to use.
>
> Indeed :). Do you have an example on how this explicit attach from
> userspace looks like? I'm already setting ATTR{driver_override} from udev,
> but that's not enough without your second patch. Should I perhaps poke in
> sysfs, somehow?
>
> > Mark quite rightly pointed out that the other driver_overrides didn't
> > automatically attach and they should all work the same way.  I made
> > patches to convert them all to automatic, but then it fell off the
> > radar and I never finished with it.
>
> If you ask me, that patch is rather simple and it enables a straightforward
> way of exporting devices to userspace. From my point of view, this is a
> desirable property.

I don't have access to an appropriate system right now, but it should be
something like:

Override $dev to spidev:

    echo spidev > /sys/bus/spi/devices/$dev/driver_override

Bind $dev to spidev:

    echo $dev > /sys/bus/spi/drivers/spidev/bind

Good luck!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds