From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754654AbaIARGR (ORCPT ); Mon, 1 Sep 2014 13:06:17 -0400 Received: from mout.kundenserver.de ([212.227.17.10]:57155 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754396AbaIARGP (ORCPT ); Mon, 1 Sep 2014 13:06:15 -0400 From: Arnd Bergmann To: Lee Jones Cc: linux-arm-kernel@lists.infradead.org, kgene.kim@samsung.com, linux@arm.linux.org.uk, naushad@samsung.com, Pankaj Dubey , Tomasz Figa , linux-kernel@vger.kernel.org, joshi@samsung.com, linux-samsung-soc@vger.kernel.org, broonie@kernel.org, thomas.ab@samsung.com, vikas.sajjan@samsung.com, chow.kim@samsung.com Subject: Re: [PATCH] mfd: syscon: Decouple syscon interface from syscon devices Date: Mon, 01 Sep 2014 19:05:51 +0200 Message-ID: <3343901.7HpqcTBEp1@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <20140901160426.GJ8796@lee--X1> References: <1408694991-21615-1-git-send-email-pankaj.dubey@samsung.com> <12348292.z1qJl96tVA@wuerfel> <20140901160426.GJ8796@lee--X1> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V02:K0:Ef3Y0k2ax7IqtvaJT/F4ShF/DsWCFsK9cWIcMMwV8SN Ql1bqPTDzTdGE2/ZiPZGyubycHTZO0eZBcKf2+o4RtgR3YpJOX RfKW+AhF9OcPZDuMCctlOvXs7PI3LEiE26v3kC19SK3VrXMcAl cyCc0hxwEIgaAHCcH3n+MFgT1g804WXTVqeuhRy5/CxqfaKYYh nghLwIv69FfWq/YaDFmk9hsQv1tsENsNxwNSWwOFeW6LHU4tfl 2zC7YKlEH7OFi/ELNExFhDUxnV27BHnwiyxifXAZZKuLHG8zfk D5HHMCTixhF/QDTBxh2cF+Sr0AehjQMk1HsiwkId8d0q21n6ja FIFBYEOxhiwRvgEolmfg= X-UI-Out-Filterresults: notjunk:1; Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 01 September 2014 17:04:26 Lee Jones wrote: > On Mon, 01 Sep 2014, Arnd Bergmann wrote: > > Maybe I'm misreading the patch, but I don't see how it creates a > > migration path. What I want to end up with is infrastructure that > > lets anybody call syscon_regmap_lookup_by_pdevname or > > syscon_regmap_lookup_by_compatible (if they really need to) > > without needing the platform_driver for syscon. That should not > > require any form of compatibility layer because to the driver > > using it there is no API change. > > Somehow I think the likelyhood is that I am misreading the patch. > > I thought that before this patch drivers we had to register a syscon > device to bind to this driver, which was fine for the first use-cases > of syscon as it wasn't required too early during boot. However, now > there are use-cases where systems require access to syscon registers > eariler in boot we require a means to obtain access prior to device > probing. I thought this patch not only provides that possibilty, but > also leaves in the ability to register direct from DT. Right, it does provide the ability to have syscon before devices are registered, I missed that part. > > In contrast, this patch introduces a new of_syscon_{un,}register() > > interface that would get removed after the the above has > > been implemented, causing extra churn for any driver that also > > wants to provide a regmap-like interface. > > When will we ever not have to register syscon? The idea is that we implicitly register the syscon block when someone calls syscon_regmap_lookup_by_compatible or syscon_regmap_lookup_by_phandle and then return a reference to that new syscon. When another driver looks up the same device node, we just pass a reference to the existing syscon. Arnd