Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751558AbdFGN0J (ORCPT ); Wed, 7 Jun 2017 09:26:09 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:34828 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751535AbdFGN0H (ORCPT ); Wed, 7 Jun 2017 09:26:07 -0400 Subject: Re: [PATCH 1/4] dt-bindings: rng: add generic bindings for MediaTek SoCs To: Sean Wang Cc: herbert@gondor.apana.org.au, mpm@selenic.com, robh+dt@kernel.org, mark.rutland@arm.com, clabbe.montjoie@gmail.com, prasannatsmkumar@gmail.com, romain.perier@free-electrons.com, shannon.nelson@oracle.com, devicetree@vger.kernel.org, keyhaede@gmail.com, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-crypto@vger.kernel.org, weiyongjun1@huawei.com, linux-arm-kernel@lists.infradead.org References: <1d9c981e1b45bf2f04732a02d90e6857cc203ce5.1496255334.git.sean.wang@mediatek.com> <9eb87222-ca89-0abb-4532-3887008f6e7a@gmail.com> <1496841619.30833.5.camel@mtkswgap22> From: Matthias Brugger Message-ID: Date: Wed, 7 Jun 2017 15:25:59 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <1496841619.30833.5.camel@mtkswgap22> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3553 Lines: 96 On 07/06/17 15:20, Sean Wang wrote: > On Tue, 2017-06-06 at 13:07 +0200, Matthias Brugger wrote: >> >> On 31/05/17 20:44, sean.wang@mediatek.com wrote: >>> From: Sean Wang >>> >>> Add the generic binding for allowing the support of RNG on MediaTek SoCs >>> such as MT7622. >>> >>> Signed-off-by: Sean Wang >>> --- >>> Documentation/devicetree/bindings/rng/mtk-rng.txt | 3 ++- >>> 1 file changed, 2 insertions(+), 1 deletion(-) >>> >>> diff --git a/Documentation/devicetree/bindings/rng/mtk-rng.txt b/Documentation/devicetree/bindings/rng/mtk-rng.txt >>> index a6d62a2..0772913 100644 >>> --- a/Documentation/devicetree/bindings/rng/mtk-rng.txt >>> +++ b/Documentation/devicetree/bindings/rng/mtk-rng.txt >>> @@ -2,7 +2,8 @@ Device-Tree bindings for Mediatek random number generator >>> found in Mediatek SoC family >>> >>> Required properties: >>> -- compatible : Should be "mediatek,mt7623-rng" >>> +- compatible : Should be "mediatek,generic-rng" or >>> + "mediatek,mt7623-rng". >> >> What does generic-rng mean. Is it for all mt7xxx, or also for mt6xxx and >> mt8xxx based SoCs? I think we should stick with SoC specific bindings, >> as we don't know if Mediatek won't publish a new IP block next year >> which is differnet. >> > > Yes, what I mean is generic-rng can be applied to all > platform MediaTek provides. > > >> Just in case we should add a binding for the actual SoC + a fallback. >> For example. >> - compatible " Should be >> "mediatek,mt7622-rng", "mediatek,mt7623-rng" for SoC mt7622 >> "mediatek,mt7623-rng" for SoC mt7623 >> >> This will also eliminate the need of adding mt6722-rng to the driver, as >> it will use mt7623-rng as fallback. If in the future we realize that >> mt7622-rng has a extra feature/bug, we can still work around it, without >> breaking the bindings. >> > > I knew the fallback rules you said here because I saw them being used in > many drivers such as sysirq and uart driver, such kind of basic drivers. > > These drivers are basic enough, various following chipsets almost fall > back into the oldest one. So the clues let me think the hardware > interface shouldn't have too much differences among them. > > If there is string used like generic-uart or generic-sysirq, it can > stop we blindly add new string into the binding document when a new > platform is introduced. > > And they easily allows users unfamiliar MediaTek platform (they didn't > know what the oldest MediaTek chipset is) pick up the right compatible > string to start bring up the new platform. > > The specific one can be added after new feature required is added or > critical hardware bug is found. Otherwise the generic one can fit > all generic needs for those. > > Those are only opinions, if you don't like it, I still can accept the > original way as you suggest :) > I can see your reasoning, but the device tree maintainers prefer to have the bindings updated for a new SoC. As I mentioned before, just imagine next year Mediatek changes the IP block and from now on, it uses the new device in all SoCs. In 5 years we would have a binding which states 'generic' although it is not compatible with any SoC of the last So So please keep with the bindings as done up to now. Best regards, Matthias > >> Makes sense? >> >> Regards, >> Matthias >> >>> - clocks : list of clock specifiers, corresponding to >>> entries in clock-names property; >>> - clock-names : Should contain "rng" entries; >>> > >