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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 ABA74C49EA2 for ; Tue, 22 Jun 2021 11:05:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 886CB6128C for ; Tue, 22 Jun 2021 11:05:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229907AbhFVLHj (ORCPT ); Tue, 22 Jun 2021 07:07:39 -0400 Received: from foss.arm.com ([217.140.110.172]:47060 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229682AbhFVLHh (ORCPT ); Tue, 22 Jun 2021 07:07:37 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0069231B; Tue, 22 Jun 2021 04:05:21 -0700 (PDT) Received: from lpieralisi (e121166-lin.cambridge.arm.com [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5302E3F694; Tue, 22 Jun 2021 04:05:19 -0700 (PDT) Date: Tue, 22 Jun 2021 12:05:17 +0100 From: Lorenzo Pieralisi To: Matthias Brugger Cc: Chen-Yu Tsai , Jianjun Wang , Ryder Lee , Bjorn Helgaas , Rob Herring , linux-pci@vger.kernel.org, linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Randy Wu , youlin.pei@mediatek.com Subject: Re: [PATCH 1/2] dt-bindings: PCI: mediatek-gen3: Add support for MT8195 Message-ID: <20210622110517.GB24565@lpieralisi> References: <20210601024408.24485-1-jianjun.wang@mediatek.com> <20210601024408.24485-2-jianjun.wang@mediatek.com> <1622526594.9054.6.camel@mhfsdcap03> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, Jun 02, 2021 at 01:33:07PM +0200, Matthias Brugger wrote: > > > On 01/06/2021 08:07, Chen-Yu Tsai wrote: > > Hi, > > > > On Tue, Jun 1, 2021 at 1:50 PM Jianjun Wang wrote: > >> > >> On Tue, 2021-06-01 at 11:53 +0800, Chen-Yu Tsai wrote: > >>> Hi, > >>> > >>> On Tue, Jun 1, 2021 at 10:50 AM Jianjun Wang wrote: > >>>> > >>>> MT8195 is an ARM platform SoC which has the same PCIe IP with MT8192. > >>> > >>> Based on what I'm seeing internally, there seems to be some inconsistency > >>> across the MediaTek platform on whether new compatible strings should be > >>> introduced for "fully compatible" IP blocks. > >>> > >>> If this hardware block in MT8195 is "the same" as the one in MT8192, do we > >>> really need the new compatible string? Are there any concerns? > >> > >> Hi Chen-Yu, > >> > >> It's ok to reuse the compatible string with MT8192, but I think this > >> will be easier to find which platforms this driver is compatible with, > >> especially when we have more and more platforms in the future. > > > > If it's just for informational purposes, then having the MT8192 compatible > > as a fallback would work, and we wouldn't need to make changes to the driver. > > This works better especially if we have to support multiple operating systems > > that use device tree. > > > > So we would want > > > > "mediatek,mt8195-pcie", "mediatek,mt8192-pcie" > > > > and > > > > "mediatek,mt8192-pcie" > > > > be the valid options. > > > > Personally I'm not seeing enough value to justify adding the compatible string > > just for informational purposes though. One could easily discern which hardware > > is used by looking at the device tree. > > > > I agree, if no differences between the two chips are known, adding a > binding withe new compatible and a fallback is a good thing. If we > later on realize that mt8195 PCI block has differences, we can add the > matching to the driver. So this series can be dropped, right ? Thanks, Lorenzo > Regards, > Matthias > > > > > Regards > > ChenYu > > > > > >> Thanks. > >>> > >>> > >>> Thanks > >>> ChenYu > >>> > >>> > >>>> Signed-off-by: Jianjun Wang > >>>> --- > >>>> Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml | 4 +++- > >>>> 1 file changed, 3 insertions(+), 1 deletion(-) > >>>> > >>>> diff --git a/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml b/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml > >>>> index e7b1f9892da4..d5e4a3e63d97 100644 > >>>> --- a/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml > >>>> +++ b/Documentation/devicetree/bindings/pci/mediatek-pcie-gen3.yaml > >>>> @@ -48,7 +48,9 @@ allOf: > >>>> > >>>> properties: > >>>> compatible: > >>>> - const: mediatek,mt8192-pcie > >>>> + oneOf: > >>>> + - const: mediatek,mt8192-pcie > >>>> + - const: mediatek,mt8195-pcie > >>>> > >>>> reg: > >>>> maxItems: 1 > >>>> -- > >>>> 2.18.0 > >>>> _______________________________________________ > >>>> Linux-mediatek mailing list > >>>> Linux-mediatek@lists.infradead.org > >>>> http://lists.infradead.org/mailman/listinfo/linux-mediatek > >>