Re: spidev: Instantiating from DT as "spidev"

[Kyle Roeschley <kyle.roeschley-acOepvfBmUk@public.gmane.org>]

On Thu, Nov 30, 2017 at 04:24:16PM -0600, Kyle Roeschley wrote:
> On Thu, Nov 30, 2017 at 09:03:12AM +0100, Geert Uytterhoeven wrote:
> > Hi Trent,
> > 
> > On Thu, Nov 30, 2017 at 3:07 AM, Trent Piepho <tpiepho-cgc2CodaaHDQT0dZR+AlfA@public.gmane.org> wrote:
> > > On Wed, 2017-11-29 at 23:18 +0100, Geert Uytterhoeven wrote:
> > >> To me, the above sounds a bit contradictive: either you have
> > >>   1. a simple (trivial) description, which can be handled by spidev and
> > >>      userspace, and thus by just writing "<unit-addr> spidev" to a new_device
> > >>      sysfs node, or
> 
> So you're suggesting that new_device can only be used to create a device which
> uses spidev (without yelling about it)? That makes sense to me.
> 
> > >>   2. a complex description, for which you need a specialized in-kernel driver,
> > >>      so you're gonna need a real DT node (and overlays?) to describe it.
> > >>
> > >> I don't think writing a complex description to a new_device sysfs node makes
> > >> sense.
> > >
> > > Is there anything one can do with new_device that can't be done with a
> > > dt fragment?
> > 
> > Nope.
> 
> Aren't DT overlays via configfs not yet in mainline? So if I did want to use
> that mechanism, I'd have call the in-kernel API from within the SPI core.
> 

Any more comments on this? If not, I'll create something like new_device and
send it up.

-- 
Kyle Roeschley
Software Engineer
National Instruments
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