Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751253AbdCRU6k (ORCPT ); Sat, 18 Mar 2017 16:58:40 -0400 Received: from mail.kernel.org ([198.145.29.136]:39276 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751187AbdCRU6i (ORCPT ); Sat, 18 Mar 2017 16:58:38 -0400 MIME-Version: 1.0 In-Reply-To: <20170315204141.1381cd01@tock> References: <1488875164-30440-1-git-send-email-albeu@free.fr> <1488875164-30440-2-git-send-email-albeu@free.fr> <20170315172401.35b5owbme4scqfgn@rob-hp-laptop> <20170315204141.1381cd01@tock> From: Rob Herring Date: Sat, 18 Mar 2017 15:58:11 -0500 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 1/2] doc: bindings: Add bindings documentation for mtd nvmem To: Alban Cc: "linux-kernel@vger.kernel.org" , Srinivas Kandagatla , Maxime Ripard , Mark Rutland , David Woodhouse , Brian Norris , Boris Brezillon , Marek Vasut , Richard Weinberger , Cyrille Pitchen , "devicetree@vger.kernel.org" , "linux-mtd@lists.infradead.org" , Moritz Fischer Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3258 Lines: 80 On Wed, Mar 15, 2017 at 2:41 PM, Alban wrote: > On Wed, 15 Mar 2017 12:24:01 -0500 > Rob Herring wrote: > >> On Tue, Mar 07, 2017 at 09:26:03AM +0100, Alban wrote: >> > Config data for drivers, like MAC addresses, is often stored in MTD. >> > Add a binding that define how such data storage can be represented in >> > device tree. >> > >> > Signed-off-by: Alban >> > --- >> > Changelog: >> > v2: * Added a "Required properties" section with the nvmem-provider >> > property >> > --- >> > .../devicetree/bindings/nvmem/mtd-nvmem.txt | 33 ++++++++++++++++++++++ >> > 1 file changed, 33 insertions(+) >> > create mode 100644 Documentation/devicetree/bindings/nvmem/mtd-nvmem.txt >> > >> > diff --git a/Documentation/devicetree/bindings/nvmem/mtd-nvmem.txt b/Documentation/devicetree/bindings/nvmem/mtd-nvmem.txt >> > new file mode 100644 >> > index 0000000..8ed25e6 >> > --- /dev/null >> > +++ b/Documentation/devicetree/bindings/nvmem/mtd-nvmem.txt >> > @@ -0,0 +1,33 @@ >> > += NVMEM in MTD = >> > + >> > +Config data for drivers, like MAC addresses, is often stored in MTD. >> > +This binding define how such data storage can be represented in device tree. >> > + >> > +An MTD can be defined as an NVMEM provider by adding the `nvmem-provider` >> > +property to their node. Data cells can then be defined as child nodes >> > +of the partition as defined in nvmem.txt. >> > + >> > +Required properties: >> > +nvmem-provider: Indicate that the device should be registered as >> > + NVMEM provider >> >> I think we should use a compatible string here (perhaps with a >> generic fallback), and that can imply it is an nvmem provider. The >> reason is then the compatible can also imply other information that >> isn't defined in DT. > > That would work for partitions but not for unpartitioned MTD as these > will already have a compatible string for the MTD hardware. I was also > under the impression that capabilities/services provided by devices > were represented with such properties, like interrupt-controller or > gpio-controller, and not with compatible strings. > > There is also another problem with unpartitioned MTD, earlier MTD > partitions binding allowed to have partitions as direct child nodes > without any compatible strings. The current nvmem binding do the same > for the nvmem cells, so it wouldn't be clear if a child node of the MTD > is a partition using the old binding or an nvmem cell. Perhaps a sign we should not repeat that. > As I think this problem could happen with some other device types I > suggested to re-work the nvmem binding to be more like the current MTD > partitions. See these threads[1][2], but a short example would look like > this: > > flash { > compatible = "vendor,flash-device-model"; > ... > nvmem-provider; > nvmem-cells { > compatible = "nvmem-cells"; Isn't the node name or compatible here enough to imply this is a nvmem provider? > #address-cells = <1>; > #size-cells = <1>; > > cell@100 { > label = "mac-address"; > reg = <0x100 0x6>; > }; > }; > };