From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 173E2C43441 for ; Mon, 12 Nov 2018 14:21:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD83E223D0 for ; Mon, 12 Nov 2018 14:21:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CD83E223D0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=pengutronix.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729956AbeKMAPZ (ORCPT ); Mon, 12 Nov 2018 19:15:25 -0500 Received: from metis.ext.pengutronix.de ([85.220.165.71]:46753 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729380AbeKMAPZ (ORCPT ); Mon, 12 Nov 2018 19:15:25 -0500 Received: from lupine.hi.pengutronix.de ([2001:67c:670:100:3ad5:47ff:feaf:1a17] helo=lupine) by metis.ext.pengutronix.de with esmtp (Exim 4.89) (envelope-from ) id 1gMD65-00084b-74; Mon, 12 Nov 2018 15:21:49 +0100 Message-ID: <1542032506.3440.5.camel@pengutronix.de> Subject: Re: [PATCH 3/4] dt-bindings: reset: uniphier: Add AHCI core reset description From: Philipp Zabel To: Kunihiko Hayashi , Masahiro Yamada Cc: Rob Herring , Mark Rutland , DTML , linux-arm-kernel , Linux Kernel Mailing List , Masami Hiramatsu , Jassi Brar Date: Mon, 12 Nov 2018 15:21:46 +0100 In-Reply-To: <20181112210215.2DB6.4A936039@socionext.com> References: <1541775663.4112.48.camel@pengutronix.de> <20181112210215.2DB6.4A936039@socionext.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1+deb9u1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:3ad5:47ff:feaf:1a17 X-SA-Exim-Mail-From: p.zabel@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Mon, 2018-11-12 at 21:02 +0900, Kunihiko Hayashi wrote: > Hi, > > Thank you for some comments and pointing out. > > On Sat, 10 Nov 2018 01:14:06 +0900 wrote: > > > On Sat, Nov 10, 2018 at 12:02 AM Philipp Zabel wrote: > > > > > > Hi Kunihiko, > > > > > > On Fri, 2018-11-09 at 10:42 +0900, Kunihiko Hayashi wrote: > > > > Add compatible strings for reset control of AHCI core implemented in > > > > UniPhier SoCs. The reset control belongs to AHCI glue layer. > > > > > > > > Signed-off-by: Kunihiko Hayashi > > > > --- > > > > Documentation/devicetree/bindings/reset/uniphier-reset.txt | 3 +++ > > > > 1 file changed, 3 insertions(+) > > > > > > > > diff --git a/Documentation/devicetree/bindings/reset/uniphier-reset.txt b/Documentation/devicetree/bindings/reset/uniphier-reset.txt > > > > index f63c511..ea00517 100644 > > > > --- a/Documentation/devicetree/bindings/reset/uniphier-reset.txt > > > > +++ b/Documentation/devicetree/bindings/reset/uniphier-reset.txt > > > > @@ -133,6 +133,9 @@ Required properties: > > > > "socionext,uniphier-pxs2-usb3-reset" - for PXs2 SoC USB3 > > > > "socionext,uniphier-ld20-usb3-reset" - for LD20 SoC USB3 > > > > "socionext,uniphier-pxs3-usb3-reset" - for PXs3 SoC USB3 > > > > + "socionext,uniphier-pro4-ahci-reset" - for Pro4 SoC AHCI > > > > + "socionext,uniphier-pxs2-ahci-reset" - for PXs2 SoC AHCI > > > > + "socionext,uniphier-pxs3-ahci-reset" - for PXs3 SoC AHCI > > > > > > Since the driver behaves identically for "socionext,uniphier-pro4-usb3- > > > reset" and "socionext,uniphier-pro4-ahci-reset", would it make sense to > > > add a common compatible? > > > > As far as I could guess, he just happened to find the same driver code > > could be reused for other hardware. Ok, in that case never mind. I just assumed that this could be a case of glue layer building blocks being reused by the hardware engineers, since the driver reuses the same clock names for USB3 and AHCI both on Pro4 and on PXs2. > > Theoretically, this can happen anywhere since > > a reset controller is just a set of registers > > each bit of which is connected to a reset line. > > > > If you added a super-generic compatible like "simple-reset", > > I would agree with > > "socionext,uniphier-pro4-usb3-reset", "simple-reset" > > since this is a pattern. > > I think it's more generic to define simple-reset with parent clock/reset > control without both SoC and device names. > > However, such parent clocks/resets strongly depends on SoC, > so I think it's difficut to lead generic definition in this case. > > If we add generic compatible string, I also add "simple-reset". There is no "simple-reset" binding definition. As soon as there are SoC specific clocks, it's not really generic anymore. > > However, > > "socionext,uniphier-pro4-glue-reset" is kind of a halfway house > > where it is SoC-specific, but still ambiguous. > > Surely, it might be hard to understand that pro4-glue-reset is SoC-specific > but for generic-device. I agree. > > > Something like: > > > "socionext,uniphier-pro4-usb3-reset", "socionext,uniphier-pro4-glue-reset" - for USB3 SoC AHCI > > > "socionext,uniphier-pro4-ahci-reset", "socionext,uniphier-pro4-glue-reset" - for Pro4 SoC AHCI > > > > > > That way if more places turn up where the glue layer reset is used, > > > you can add them without patching the driver every time. > > > > > > This is a trade-off between "patch the driver" > > and "potential change of the binding". > > Adding "glue-reset" is usable for devices having same parent clocks/resets as > usb3/ahci, and we can add the devices without patches. > > However, if the device needs other parent clocks/resets for the same SoC, > we can't add "glue-reset" and we might add patches for the device as a result. > In this case, the "glue-reset" will become difficult to understand. Then let's not bother with it. I made the suggestion without knowing the full picture. > > There is no real hardware like pro4-glue-reset. > > > > I am guessing this is a part of syscon or something, > > but I cannot find any explanation in a bigger picture. > > > > So, I cannot judge this further more. > > Since it's hard to lead the best result, > currently I'd like to suggest the current compatibles, That is fine with me. > with "simple-reset" if necessary. Not necessary. best regards Philipp