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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 794CFFA3743 for ; Tue, 1 Nov 2022 13:04:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229867AbiKANEo (ORCPT ); Tue, 1 Nov 2022 09:04:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43220 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229783AbiKANEj (ORCPT ); Tue, 1 Nov 2022 09:04:39 -0400 Received: from fllv0015.ext.ti.com (fllv0015.ext.ti.com [198.47.19.141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 509C11A82D; Tue, 1 Nov 2022 06:04:38 -0700 (PDT) Received: from fllv0035.itg.ti.com ([10.64.41.0]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id 2A1D4G1m001796; Tue, 1 Nov 2022 08:04:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1667307856; bh=62S3+g55ZcTL/pb8O/4q9XR3gQaDxdYkksjQkw57tqI=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=aSUD/339RcZ7DYNKUDBh4E/zIamTYf2HirW3uI9X8GK/tex5iFK2aVE7ACnu7O9k9 JNoLfZnEi50wYYpsLrM3Re6iGzasB9TSb0U4I/jhd+6BB5lSuOUUw8penqPvEeXrGf qIcjQ7jFoPfD2krjyDcUFiLz5LdaVgq1qF+W56lk= Received: from DLEE108.ent.ti.com (dlee108.ent.ti.com [157.170.170.38]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 2A1D4GBk038199 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 1 Nov 2022 08:04:16 -0500 Received: from DLEE105.ent.ti.com (157.170.170.35) by DLEE108.ent.ti.com (157.170.170.38) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.6; Tue, 1 Nov 2022 08:04:15 -0500 Received: from lelv0327.itg.ti.com (10.180.67.183) by DLEE105.ent.ti.com (157.170.170.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2507.6 via Frontend Transport; Tue, 1 Nov 2022 08:04:15 -0500 Received: from [10.250.35.234] (ileaxei01-snat.itg.ti.com [10.180.69.5]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id 2A1D4FXG058015; Tue, 1 Nov 2022 08:04:15 -0500 Message-ID: <2a7afcc3-b973-c993-e4f1-0f1888073f28@ti.com> Date: Tue, 1 Nov 2022 08:04:15 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.2 Subject: Re: [PATCH v3 2/9] ARM: dts: nspire: Use syscon-reboot to handle restart To: Rob Herring CC: Krzysztof Kozlowski , Lee Jones , Krzysztof Kozlowski , Arnd Bergmann , Linus Walleij , Geert Uytterhoeven , Daniel Tang , Fabian Vogt , , , References: <20221027181337.8651-1-afd@ti.com> <20221027181337.8651-3-afd@ti.com> <050f3d65-5720-9c97-1930-bc458c4c2fb8@linaro.org> <4236ab07-6ad3-efcd-7d5e-c244581d2944@linaro.org> <0025ec36-0632-b79e-beba-cf838018a704@ti.com> <20221031171430.GA2981736-robh@kernel.org> Content-Language: en-US From: Andrew Davis In-Reply-To: <20221031171430.GA2981736-robh@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/31/22 12:14 PM, Rob Herring wrote: > On Mon, Oct 31, 2022 at 09:30:45AM -0500, Andrew Davis wrote: >> On 10/27/22 4:27 PM, Krzysztof Kozlowski wrote: >>> On 27/10/2022 17:07, Andrew Davis wrote: >>>> On 10/27/22 2:33 PM, Krzysztof Kozlowski wrote: >>>>> On 27/10/2022 14:13, Andrew Davis wrote: >>>>>> Writing this bit can be handled by the syscon-reboot driver. >>>>>> Add this node to DT. >>>>>> >>>>>> Signed-off-by: Andrew Davis >>>>>> Reviewed-by: Linus Walleij >>>>>> Tested-by: Fabian Vogt >>>>>> Reviewed-by: Fabian Vogt >>>>>> --- >>>>>> arch/arm/boot/dts/nspire.dtsi | 7 +++++++ >>>>>> 1 file changed, 7 insertions(+) >>>>>> >>>>>> diff --git a/arch/arm/boot/dts/nspire.dtsi b/arch/arm/boot/dts/nspire.dtsi >>>>>> index bb240e6a3a6f..48fbc9d533c3 100644 >>>>>> --- a/arch/arm/boot/dts/nspire.dtsi >>>>>> +++ b/arch/arm/boot/dts/nspire.dtsi >>>>>> @@ -172,7 +172,14 @@ rtc: rtc@90090000 { >>>>>> }; >>>>>> misc: misc@900a0000 { >>>>>> + compatible = "ti,nspire-misc", "syscon", "simple-mfd"; >>>>> >>>>> You have syscon and simple-mfd, but bindings in patch #1 say only syscon. >>>>> >>>> >>>> I'm not following, are you just saying my wording in the patch message just >>>> wasn't complete? >>> >>> Your binding patch adds nspire compatible to the list of two items, so >>> you have two items in total - nspire followed by syscon. >>> >>> What you implemented here is different. >>> >> >> Is there a list of three items I can add this compatible? If instead you >> mean I should go make a new binding, just say so :) > > An MFD should define its own schema file. > > The original intent of syscon.yaml was for just single nodes with > 'syscon' (and a specific compatible). Adding in simple-mfd was probably > a mistake. Certainly we need to rework the schema as you should get a > warning in this case. > >>>> Or are you saying something more about nodes that are both syscon and simple-mfd? >>>> In that case, having both syscon and simple-mfd seems rather common, looks like >>>> you added the rule for it[0]. >>>> >>>> Thinking on this, they almost represent the same thing. simple-mfd says "my child >>>> nodes should be considered devices", why do we need that? Couldn't we simply state >>>> that "syscon" node's children are always devices, I mean what else could they be, >>>> syscon is an MFD after all (and lives in drivers/mfd/). >>> >>> No, syscon is not an MFD. Syscon means system controller and alone it >>> does not have children. >>> >> >> The binding lives in devicetree/bindings/*mfd*/, it is mentioned as one >> in devicetree/bindings/mfd/mfd.txt. If it is not an MFD then the bindings >> are giving out mixed signals here.. >> >>>> >>>> "syscon" often just says, others can use the registers within this node, so as a >>>> different option, make "syscon" a property of "simple-mfd" nodes. I'm seeing all >>>> these examples of devices that should have been children of the "syscon" device, >>>> but instead use >>>> >>>> regmap = <&x>; >>>> syscon = <&x>; >>>> >>>> or similar and put the device node out somewhere random. And in those cases, >>>> wouldn't it have been more correct to use the normal "reg" and "regions" to >>>> define the registers belonging to the child node/device?.. >>> >>> Sorry, I do not follow. How this is even related to your patch? >>> >>> Your bindings say A, DTS say B. A != B. This needs fixing. >>> >> >> I said it was compatible with "syscon", not that it is incompatible >> with "simple-mfd" devices. >> >> What I've done here gives no dtbs_check warnings and >> "devicetree/bindings/mfd/mfd.txt" explicitly allows what I am doing. >> Unless we do not consider the old bindings valid? > > Only that the example is not because it doesn't have a specific > compatible. > > What needs to be clarified is that MFDs must define all the child nodes > whether they are 'simple' or not. > >> If so, would you >> like me to convert mfd.txt to yaml, just let me know. > > No, because I don't think there is anything to define as a schema. > It would allow for simple register regions to be 'simple-mfd' without needing a whole new binding document for each. Same as we already have with 'syscon.yaml'. Making every simple MMIO space create a new binding document is not reasonable. Neither is defining all nodes up front in that binding, we don't expect that for top level nodes or 'simple-bus', why should we for 'simple-mfd'? My point with mfd.txt is that this *was allowed*, and there are already a large number of users of the existing style. > >>> Unless you are asking me what your device is in general. This I don't >>> really know, but if you want to use it as regmap provider for system >>> registers and as a parent of syscon-based reboot device, then your >>> device is syscon and simple-mfd. With a specific compatible. Was this >>> your question? >>> >> >> Yes, I would like to use it as a regmap provider, my question here is >> a much more general one: why do I need to specify that in device tree? >> That is not a hardware description, my hardware is not "regmap" hardware. >> This "syscon" stuff feels like a bodge to make the Linux drivers and bus >> frameworks interact the way we want. > > Bingo! It's a hint for create a regmap. We could just have a compatible > list in the kernel for compatibles needing a regmap. Maybe that list > would be too long though. So call it h/w description for this h/w is > referenced by other places. > > >> I know at this point this has little to do with this series, but I'd like >> to just think this out for a moment. The latest Devicetree Specification >> talks about "simple-bus" as a special compatible that communicates that >> child nodes with compatible strings need probed also. ("simple-mfd" seems >> to be used the same way but without needing a "ranges" property..) > > Yes, both cases are saying there is no dependency or setup of the parent > needs. If the child nodes depend on the regmap, then it's not a > 'simple-mfd' IMO. Therefore 'syscon' together with 'simple-mfd' is wrong > unless it's other nodes that need the regmap. The schema can't really > check that. > 'syscon' also provides for reusing the same single register by multiple users, such as bit-mapped registers. It also allows re-using the existing simple syscon device compatibles. Again because people do not like writing bindings for simple nodes. Andrew >> Both of these are properties of a node, not something a device is "compatible" >> with. "compatibles" are also supposed to be listed "from most specific to >> most general", so which is more specific, "simple-mfd" or "syscon", etc.. > > I would say 'syscon' is more specific if I have to pick. It implies some > registers exist. 'simple-mfd' should mean there are no parent resources > (...the children depend on). > > We've probably got enough of a mixture of the order, it wouldn't be > worth the effort to try to enforce the order here. > >> Seems like Rob might agree[0], these are not really compatibles. We cant fix >> history, but for new nodes, instead of growing the problem and forcing these to >> be overloaded compatibles, we allow these to become new standard node properties. >> >> For instance: >> >> main_conf: syscon@43000000 { >> compatible = "ti,j721e-system-controller"; >> reg = <0x0 0x43000000 0x0 0x20000>; >> >> simple-bus; >> syscon; > > Umm, no. This ship already sailed and we don't need a 2nd way to do > things. > > Rob