From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753437AbaIAL0A (ORCPT ); Mon, 1 Sep 2014 07:26:00 -0400 Received: from mail-ig0-f174.google.com ([209.85.213.174]:48297 "EHLO mail-ig0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751439AbaIALZ5 (ORCPT ); Mon, 1 Sep 2014 07:25:57 -0400 Date: Mon, 1 Sep 2014 12:25:49 +0100 From: Lee Jones To: Arnd Bergmann Cc: Pankaj Dubey , linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-kernel@vger.kernel.org, kgene.kim@samsung.com, linux@arm.linux.org.uk, vikas.sajjan@samsung.com, joshi@samsung.com, naushad@samsung.com, thomas.ab@samsung.com, chow.kim@samsung.com, Tomasz Figa , broonie@kernel.org Subject: Re: [PATCH] mfd: syscon: Decouple syscon interface from syscon devices Message-ID: <20140901112549.GM7374@lee--X1> References: <1408694991-21615-1-git-send-email-pankaj.dubey@samsung.com> <20140901074918.GB6226@lee--X1> <4121644.3haxjiIdIo@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4121644.3haxjiIdIo@wuerfel> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 01 Sep 2014, Arnd Bergmann wrote: > On Monday 01 September 2014 08:49:18 Lee Jones wrote: > > On Fri, 22 Aug 2014, Pankaj Dubey wrote: > > > > > From: Tomasz Figa > > > > > > Currently a syscon entity can be only registered directly through a > > > platform device that binds to a dedicated driver. However in certain use > > > cases it is desirable to make a device used with another driver a syscon > > > interface provider. For example, certain SoCs (e.g. Exynos) contain > > > system controller blocks which perform various functions such as power > > > domain control, CPU power management, low power mode control, but in > > > addition contain certain IP integration glue, such as various signal > > > masks, coprocessor power control, etc. In such case, there is a need to > > > have a dedicated driver for such system controller but also share > > > registers with other drivers. The latter is where the syscon interface > > > is helpful. > > > > > > This patch decouples syscon object from syscon driver, so that it can be > > > registered from any driver in addition to the original "syscon" platform > > > driver. > > > > > > Signed-off-by: Tomasz Figa > > > Signed-off-by: Pankaj Dubey > > > --- > > > > > > RFC patch [1] was posted by Tomasz Figa. This patch addresses some of > > > comments given by Arnd to RFC patch, and further decouples syscon from > > > device model. It also gives flexibility of registering with syscon at > > > early stage using device_node object. > > > > It would be helpful if Arnd gave this revision his blessing (Ack). > > I never saw a reason why we don't take this all the way as discussed > a few times: Completely remove the dependency of syscon on having > a platform driver for it, and make it possible to just call > syscon_regmap_lookup_by_phandle() without having to register > it first. I think this sounds like a good end-state. Migrating over by supporting both methods in this way does sound like the correct thing to do though. Doing so is likely to dramatically reduce the effect on current users. -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog