From mboxrd@z Thu Jan 1 00:00:00 1970 From: Darren Hart Subject: Re: [PATCH v4 00/13] Add ACPI _DSD and unified device properties support Date: Wed, 15 Oct 2014 16:46:39 +0200 Message-ID: <543E88CF.5060504@linux.intel.com> References: <2660541.BycO7TFnA2@vostro.rjw.lan> <1413378271.2762.77.camel@infradead.org> <20141015131551.GC20034@leverpostej> <1413379736.2762.79.camel@infradead.org> <20141015134209.GD20034@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org To: David Woodhouse , Mark Rutland Cc: "Rafael J. Wysocki" , Linux Kernel Mailing List , Greg Kroah-Hartman , Mika Westerberg , ACPI Devel Maling List , Aaron Lu , "devicetree@vger.kernel.org" , Linus Walleij , Alexandre Courbot , Dmitry Torokhov , Bryan Wu , "grant.likely@linaro.org" , Arnd Bergmann , dvhart@infradead.org List-Id: devicetree@vger.kernel.org On 10/15/14 16:08, David Woodhouse wrote: > >> We have been checking for all DT platforms, and that's a bug for DT. >> Copying that bug to ACPI is inexcusable given we know it's a bug to do >> so. > > We'll, perhaps it should be named 'used-by-firmware' and actually it's > just as valid under ACPI as it is on RTAS systems. All it does is stop the > OS from using the port. > >> I understand that. However, where a binding doesn't make sense (as in >> this case), it shouldn't be enabled for ACPI as it provides a larger >> surface area for misuse, for no benefit. > > These are *optional* properties. They were optional precisely *because* > they only make sense in some cases. I don't know that it makes sense to > take them away. The benefit we get is *consistency*. For example if > someone *does* use the property in question as 'used-by-firmware' and > expects the OS not to touch it, we don't want that to change behaviour > between ACPI and fdt boots. My comment was going to be along the same lines. It is an optional parameter, which is what I would expect for a firmware-specific type of property. I also don't agree that this is "copying that bug to ACPI". This line of code has no impact to ACPI. No ACPI implementation should add this, certainly not if it was actually tested as it would not run if it was present in the _DSD. So... what's the problem exactly? Or perhaps more specifically: Mark, what would you propose we do differently to enable this driver to be firmware-type agnostic? -- Darren Hart Intel Open Source Technology Center