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[209.132.180.67]) by mx.google.com with ESMTP id j10si15003015plb.346.2019.05.13.00.42.44; Mon, 13 May 2019 00:42:59 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727777AbfEMHLe convert rfc822-to-8bit (ORCPT + 99 others); Mon, 13 May 2019 03:11:34 -0400 Received: from mail-vs1-f66.google.com ([209.85.217.66]:36200 "EHLO mail-vs1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726841AbfEMHLd (ORCPT ); Mon, 13 May 2019 03:11:33 -0400 Received: by mail-vs1-f66.google.com with SMTP id c76so7358097vsd.3; Mon, 13 May 2019 00:11:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=AwLnfNDWLBJHzIjiUSN0rlrxnWBlC6Tvjo4enXu1mhg=; b=Egg7OwyxiZAhSSAOSbKVmc/SO5wdRM76/aQcvV1MdkP5n+zmM4uULUGS0k1vsllcVr dfYF5kU28zxa9slh0/orKuPuzRaL+l4e1H2SjDQRB1yP622RjdtdNq47e+6mdeiARbBR sFMs39d4c+gk0mgIyq3f9M07ec7apZMgEi+XrUbODCR03cT3VIeiNcP/zamnVmpo/5Xw ILDXHv38owiMCxOkDdGR2e0jvwJoAy+CvsXOn9h9QtFdfwu1ZxekcVG3PjwM0VILzhCs QPxVawQdo11AG/rVuN+oa7Lb1485MjqB7HD7D4AxVzpe+cCkk0r0tCMxQg1gWn+eD4W/ iWfQ== X-Gm-Message-State: APjAAAXZxWtUOgsugJ5+3qV1dC5J+nBtaKMlivG2AeneO1kQkW7aUMli nk+2QoKKB2AO5h4EOnunjRhvBqAwI0prIU76FVA= X-Received: by 2002:a67:f303:: with SMTP id p3mr1137935vsf.166.1557731491713; Mon, 13 May 2019 00:11:31 -0700 (PDT) MIME-Version: 1.0 References: <1556092536-17095-1-git-send-email-masonccyang@mxic.com.tw> <1556092536-17095-4-git-send-email-masonccyang@mxic.com.tw> <20190424212356.GA27103@bogus> <65853dc2-6f3c-1494-7e72-54877797cdd2@gmail.com> <20190507125730.GD29524@dell> <20190508061119.GB7627@dell> In-Reply-To: From: Geert Uytterhoeven Date: Mon, 13 May 2019 09:11:19 +0200 Message-ID: Subject: Re: [PATCH v12 3/3] dt-bindings: mfd: Document Renesas R-Car Gen3 RPC-IF MFD bindings To: Mason Yang Cc: Sergei Shtylyov , Lee Jones , Marek Vasut , Boris Brezillon , Mark Brown , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Geert Uytterhoeven , Simon Horman , juliensu@mxic.com.tw, Linux Kernel Mailing List , Linux-Renesas , linux-spi , Mark Rutland , Rob Herring , zhengxunli@mxic.com.tw Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mason, On Fri, May 10, 2019 at 3:09 AM wrote: > > "Sergei Shtylyov" > > 2019/05/10 上午 03:24 > > mark.rutland@arm.com, "Rob Herring" , zhengxunli@mxic.com.tw > > On 05/09/2019 05:06 AM, masonccyang@mxic.com.tw wrote: > > > > [...] > > >> > >> > On 4/24/19 11:23 PM, Rob Herring wrote: > > >> > >> > > On Wed, Apr 24, 2019 at 03:55:36PM +0800, Mason Yang wrote: > > >> > >> > >> Document the bindings used by the Renesas R-Car Gen3 RPC-IF MFD. > > >> > >> > >> > > >> > >> > >> Signed-off-by: Mason Yang > > >> > >> > >> --- > > >> > >> > >> .../devicetree/bindings/mfd/mfd-renesas-rpc.txt | 40 ++++++ > > >> > >> ++++++++++++++++ > > >> > >> > >> 1 file changed, 40 insertions(+) > > >> > >> > >> create mode 100644 Documentation/devicetree/bindings/mfd/mfd- > > >> > >> renesas-rpc.txt > > >> > >> > >> > > >> > >> > >> diff --git a/Documentation/devicetree/bindings/mfd/mfd-renesas- > > >> > >> rpc.txt b/Documentation/devicetree/bindings/mfd/mfd-renesas-rpc.txt > > >> > >> > >> new file mode 100644 > > >> > >> > >> index 0000000..668b822 > > >> > >> > >> --- /dev/null > > >> > >> > >> +++ b/Documentation/devicetree/bindings/mfd/mfd-renesas-rpc.txt > > >> > >> > >> @@ -0,0 +1,40 @@ > > >> > >> > >> +Renesas R-Car Gen3 RPC-IF MFD Device Tree Bindings > > >> > >> > >> +-------------------------------------------------- > > >> > >> > > > > >> > >> > > Looks like a SPI flash controller from the example. What > > makes it an > > >> > >> > > MFD? > > >> > >> > > > >> > >> > It supports both SPI NOR and HyperFlash (CFI-compliant flash with > > >> > >> > different bus interface). > > >> > >> > > >> > >> Looks like you're registering one OR the other. > > >> > >> > > >> > >> Why don't you just do this from DT? > > >> > >> > > >> > >> No reason for this to be an MFD IMHO. > > >> > > > > >> > > > > >> > > okay, I will patch it back to SPI mode only. > > >> > > > >> > I don't think that's what Lee meant . The controller supports _both_ > > >> > modes , hence it would have the same compatible string. You just need to > > >> > extract the mode of operation from the DT. > > >> > > >> HiSilicon attempted to upstream something similar, only their > > >> controller provided NAND and NOR functionality. They used different > > >> compatible strings to differentiate between the varying > > >> technologies. > > >> > > >> They too tried to use MFD as a means to select between them (which was > > >> also NACKed). Not sure what they ended up doing, but the original > > >> submission and (half of) the conversation can be found at [0]. Some > > >> more of the thread continues at [1]. > > >> > > >> Hope that helps. > > >> > > >> [0] https://groups.google.com/forum/#!topic/fa.linux.kernel/F6i9o8sfOIw > > >> [1] https://marc.info/?l=devicetree&m=147669165104431&w=2 > > > > > > > > > Hi Marek, > > > > > > By Jones's comments: > > > -------------------------------------------------------------------------- > > >> From: Shunquan Lin > > >> > > >> This patch adds driver support for HiSilicon Flash Memory > > >> Controller(FMC). HiSilicon FMC is a multi-functions device which > > >> supports SPI Nor flash controller, SPI nand Flash controller and > > >> parallel nand flash controller. > > > > > > MFDs are for devices which span multiple subsystems. > > > > And we do! One of the subdrivers will live under drivers/spi/, the other > > under drivers/mtd/... > > > > From my point of view, I think Jones mean to MFD's subsystems are working simultaneously > at the run-time, one period of time is working for sub-device-1 and later period of time > is working for sub-device-2 and so on. > > But for RPC-IF, SPI or HF mode is decided at boot time by pins configure and later in kernel > by dtb, RPC-IF can't switch SPI and HF mode at the run time. > So far, Jones seems don't agree RPC-IF to MFD and then RPC MFD will not applied > to mfd tree by him ! There's precedence for such constructs being an MFD: please see drivers/mfd/at91-usart.c, which registers a single MFD cell for either serial or SPI. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds