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[209.132.180.67]) by mx.google.com with ESMTP id g13si16718163pgj.272.2019.05.13.09.13.13; Mon, 13 May 2019 09:13:30 -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 S1730805AbfEMOnY (ORCPT + 99 others); Mon, 13 May 2019 10:43:24 -0400 Received: from mail-vs1-f65.google.com ([209.85.217.65]:39457 "EHLO mail-vs1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729893AbfEMOnY (ORCPT ); Mon, 13 May 2019 10:43:24 -0400 Received: by mail-vs1-f65.google.com with SMTP id m1so1003717vsr.6; Mon, 13 May 2019 07:43:23 -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; bh=ClzU7jZAryaIXzR+/qv1yEuyi15Ak7Jc5yYHkm+jUlE=; b=UHSBnBwRKi2PsFkZS/Y1M9KW5l+UG/SNvzsM00vj10nq1Ur8+7/V1Ead9gAxfLWbW+ tAL2s0kU2TRouxv2tuXytbyyGrcg9s1iyh/8OrDSRzpEJY58MH/fEdn4HnhSvT7JxoMn /3yb2yQ1KeWeqhLR8wf+C3SYwMB0BTDCAMksnfnninUpvJp4onyxWrb1apce6wvAmsgl o/RBEa8ZxVfQLhNMJ0LPgMmtagsYhnUVzjRZzjNEMHwjYUqRFWmESVC2caKr54t2WDjN ZaZjHe7aUhYNficbc7yxbHb0oYgguBCuXHwIyfO+Rhh2gBSQCb9NCMM7dAXMHN23VAIU 2cJQ== X-Gm-Message-State: APjAAAWrcC/Lee2T4klztruJtBjWFIE0toUaWi30BtobsuODaZhXcmUY L5pducjb035/MF8CR1Gyv5GBXPpZE4Hb9RjLMs0= X-Received: by 2002:a67:f303:: with SMTP id p3mr2137246vsf.166.1557758602639; Mon, 13 May 2019 07:43:22 -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 16:43:09 +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: Boris Brezillon , Mark Brown , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Geert Uytterhoeven , Simon Horman , juliensu@mxic.com.tw, Lee Jones , Linux Kernel Mailing List , Linux-Renesas , linux-spi , Marek Vasut , Mark Rutland , Rob Herring , Sergei Shtylyov , zhengxunli@mxic.com.tw Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mason, Note that if you send multipart/text+html emails, they will be dropped silently by most Linux mailing lists. Hence I'm quoting your last email fully, to give other people a chance reading it (and commenting). On Mon, May 13, 2019 at 11:37 AM 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-compliantflash 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. > > okay, many thanks for your information. > > How about to patch RPF-IF dts to: > --------------------------------------------------------------> > > Renesas R-Car Gen3 RPC-IF controller Device Tree Bindings > --------------------------------------------------------- > > RPC-IF supports both SPI NOR and HyperFlash (CFI-compliant flash) > > Required properties: > - compatible: should be an SoC-specific compatible value, followed by > "renesas,rcar-gen3-rpc" as a fallback. > supported SoC-specific values are: > "renesas,r8a77995-rpc" (R-Car D3) > - reg: should contain three register areas: > first for the base address of RPC-IF registers, > second for the direct mapping read mode and > third for the write buffer area. > - reg-names: should contain "regs", "dirmap" and "wbuf" > - clocks: should contain 1 entries for the module's clock > - clock-names: should contain "rpc" > > Example: > - SPI mode: > > rpc: rpc-if@ee200000 { > compatible = "renesas,r8a77995-rpc", "renesas,rcar-gen3-rpc"; > reg = <0 0xee200000 0 0x200>, <0 0x08000000 0 0x4000000>, > <0 0xee208000 0 0x100>; > reg-names = "regs", "dirmap", "wbuf"; > clocks = <&cpg CPG_MOD 917>; > clock-names = "rpc"; > power-domains = <&sysc R8A77995_PD_ALWAYS_ON>; > resets = <&cpg 917>; > #address-cells = <1>; > #size-cells = <0>; > > flash@0 { > compatible = "jedec,spi-nor"; > reg = <0>; > spi-max-frequency = <40000000>; > spi-tx-bus-width = <1>; > spi-rx-bus-width = <1>; > }; > }; > > - HF mode: > rpc: rpc-if@ee200000 { > compatible = "renesas,r8a77995-rpc", "renesas,rcar-gen3-rpc"; > reg = <0 0xee200000 0 0x200>, <0 0x08000000 0 0x4000000>, > <0 0xee208000 0 0x100>; > reg-names = "regs", "dirmap", "wbuf"; > clocks = <&cpg CPG_MOD 917>; > clock-names = "rpc"; > power-domains = <&sysc R8A77995_PD_ALWAYS_ON>; > resets = <&cpg 917>; > #address-cells = <1>; > #size-cells = <1>; > > flash@0 { > compatible = "cfi-flash"; > reg = <0 0x4000000>; > }; > }; > > --------------------------------------------------------------< > > Is it OK ? I'll defer to the MTD experts. 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