From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTP id D6BB796D for ; Sat, 17 May 2014 03:20:34 +0000 (UTC) Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 85BB6201A9 for ; Sat, 17 May 2014 03:20:34 +0000 (UTC) Received: by mail-pa0-f45.google.com with SMTP id ey11so3324314pad.4 for ; Fri, 16 May 2014 20:20:34 -0700 (PDT) Sender: Darren Hart Message-ID: <1400295744.9575.104.camel@wasp-deb.dvhart.com> From: Darren Vincent Hart To: Arnd Bergmann Date: Fri, 16 May 2014 20:02:24 -0700 In-Reply-To: <4779952.HbUGmSHJeO@wuerfel> References: <11391971.y9GOPHmK72@wuerfel> <20140513211442.GB28268@quad.lixom.net> <4779952.HbUGmSHJeO@wuerfel> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , ksummit-discuss@lists.linuxfoundation.org Subject: Re: [Ksummit-discuss] [TECH TOPIC] Driver model/resources, ACPI, DT, etc (sigh) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2014-05-14 at 14:06 +0200, Arnd Bergmann wrote: > On Tuesday 13 May 2014 14:14:42 Olof Johansson wrote: > > On Tue, May 06, 2014 at 03:35:41PM +0200, Arnd Bergmann wrote: > > > On Tuesday 06 May 2014 14:18:56 Rafael J. Wysocki wrote: > > > > > > We should definitely be able to have an interface like this for > > > ACPI, but you don't have a 'struct device_node' pointer then. > > > We can add a new > > > > > > bool dev_property_read_bool(const struct device *dev, > > > const char *propname); > > > > > > > > that handles both, but then you have to change every driver > > > that is already using of_property_read_bool() and that can > > > get used with ACPI. > > > > It's actually not that easy in practice. There's not a one-to-one > > correspondence between device tree nodes and struct devices in the > > kernel. There are many bindings that use subnodes for sections of their > > information, and so on. > > I also don't think we can have a grand unified solution to the general > problem, but doing the above would solve a lot of individual problems > for all the simple drivers that don't use sub-nodes in DT. > > I really don't see any downsides to using a common named property > API for simple values in drivers that can. > > Devices with sub-nodes are by definition complex to handle, and > I think we will always have cases that are too complex to use > a common interface. At the moment, we can share drivers that > have only memory and irq resources, which is a significant share > already. We can over time extend this to drivers that use strings, > booleans, integers, or arrays of those. We can also extend it > for things like gpios and dma-channels (both of which partly work > already but are limited when it comes to naming) and a few other > things. Agreed, well said. -- Darren Hart Intel Open Source Technology Center