From: Arnd Bergmann <arnd@arndb.de>
To: Darren Hart <dvhart@linux.intel.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>, linux-kernel@vger.kernel.org,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        linux-acpi@vger.kernel.org, devicetree@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Alexandre Courbot <gnurou@gmail.com>, Bryan Wu <cooloney@gmail.com>,
        Lee Jones <lee.jones@linaro.org>,
        Grant Likely <grant.likely@linaro.org>, Aaron Lu <aaron.lu@intel.com>
Subject: Re: [PATCH v3 10/15] leds: leds-gpio: Add ACPI probing support
Date: Wed, 01 Oct 2014 20:22:36 +0200
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On Wednesday 01 October 2014 11:11:46 Darren Hart wrote:
> >
> >No, I think in absence of drv->acpi_match_table ACPI core should just go
> >and
> >use drv->of_match_table to do the matching and be done with it.
> 
> But then you will match drivers that have of-only support that don't know
> anything about ACPI and haven't been updated to use the new API. Worse,
> some of those drivers will assume of node structs and such and potentially
> panic. Unless I'm sorry mistaken here....
> 

I don't think that is a huge danger: most drivers tend to check for
the presence of dev->of_node before calling any of the DT interfaces,
you'd only ever enter the probe function if the compatible string matches
(i.e. an old kernel with a new ACPI table), and most users of ACPI
systems will disable CONFIG_OF at compile time, so the accessors looking
at the of_node are not there.

In theory it's possible that something goes wrong here, but it's not
very likely to ever cause problems.

	Arnd
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