Re: [PATCH] wmi: Set wmi devices' parents

[Darren Hart <dvhart@infradead.org>]

On Thu, Nov 26, 2015 at 03:09:29PM +0100, Rafael Wysocki wrote:
> On Wednesday, November 25, 2015 05:28:54 PM Andy Lutomirski wrote:
> > On Mon, Nov 23, 2015 at 11:37 AM, Darren Hart <dvhart@infradead.org> wrote:
> > > On Mon, Nov 23, 2015 at 11:25:30AM -0800, Andy Lutomirski wrote:
> > >> Without this patch, wmi devices are in /sys/virtual/wmi.  They're
> > >> logically children of the ACPI WMI device, so slot them into the
> > >> device hierarchy.  With this change, on my laptop, they end up in
> > >> /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C14:00/wmi and
> > >> /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C14:01/wmi.
> > >>
> > >> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> > >
> > > I'd like to hear from some of the main contributors to this driver:
> > >
> > > Matthew?
> > > Carlos?
> > > Len?
> > >
> > > Any cocnerns on this change?
> > >
> > > My initial concern is about changign how we expose this to userspace, but I
> > > believe where it appears in the /sys/devices FS is NOT part of the
> > > kernel-userspace interface commitment (per sysfs-rules.txt).
> > 
> > 
> > Let's drop this, actually.  I have mostly-working patches to make wmi
> > into an actual bus driver, and this intermediate step seems like it'll
> > just confuse people.
> > 
> > Question, though: where do the WMI devices belong?  Multiple choice:
> > 
> > /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C14:01/[GUID]
> > 
> > /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C14:01/wmi/[GUID]
> > 
> > /sys/devices/platform/PNP0C14:01/[GUID]
> > 
> > /sys/devices/platform/PNP0C14:01/wmi/[GUID]
> > 
> > Currently I've implemented the first one because it's the smallest diff.
> 
> That probably is not the right choice, though.
> 
> ACPI "devices" are counterparts of DT device nodes and having other things
> exported under them would be quite confusing.  In fact, you can argue that
> the whole /sys/devices/LNXSYSTM:00/ directory should be located under
> /sys/firmware/acpi, but it turns out to be difficult to move it there
> for various reasons.
> 
> Personally, I'd go for the last one.

That looks like a logical place to me.

-- 
Darren Hart
Intel Open Source Technology Center