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From: Arnd Bergmann <arnd@arndb.de>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, devicetree@vger.kernel.org,
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        Dmitry Torokhov <dmitry.torokhov@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>,
        Darren Hart <dvhart@linux.intel.com>
Subject: Re: [PATCH v3 10/15] leds: leds-gpio: Add ACPI probing support
Date: Wed, 01 Oct 2014 12:01:34 +0200
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On Wednesday 01 October 2014 12:13:09 Mika Westerberg wrote:
> 
> > Regarding the MODULE_DEVICE_TABLE, I suspect the above won't work the
> > way you are hoping for, because once you get to dozens or hundreds of
> > drivers doing this, each device will show up with the same string,
> > so udev will try to load all the modules that list "PRP0001". That
> > doesn't look right. With the code from patch 3, you can probably drop
> > the acpi MODULE_DEVICE_TABLE() entirely and get the correct behavior.
> 
> It actually works like this now:
> 
>  # cd /sys/bus/platform/devices/PRP0001\:00/
>  DRIVER=leds-gpio
>  MODALIAS=of:Nprp0001TacpiCgpio-leds
> 
>  # cat modalias 
>  of:Nprp0001TacpiCgpio-leds
> 
> In other words the modalias changes to be of:Nprp0001Tacpi, e.g
> name=prp0001, type=acpi and then list of compatible values.
> 
> Udev then loads only module that matches the modalias so it should not
> load everything listing PRP0001 in their MODULE_DEVICE_TABLE().

I'm not completely following yet. I can see how this works now, but
how is this better than just using the existing modalias for OF?

	Arnd