From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ahti.lucaweiss.eu (ahti.lucaweiss.eu [128.199.32.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 73827364A9; Fri, 24 May 2024 17:55:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=128.199.32.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716573330; cv=none; b=oUBQecgFzIxfYTZTn4sfzvSZDLARbn1DMYX6RLjoPeolyUyv4c3PHKMartMWC18akeBBH521Od9ulJ5YhdDn+8lDAMf78/RrmELJ1Cokk6gbJ5hgDUf3Ug2rYbYXwtotnprSq40FAuNfFNaKGfefe4ifNCCXH6dKVkzxHvsJG6M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716573330; c=relaxed/simple; bh=NE3+asARG+T0s+9Kmlx2qtu/4uK3J6MB1QLPal+bElU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=SfdUOBh3xCt3ZTsW2Ydp5qoK8GrycEmNh/qrF1eJSftPhEBwHsUgKCpTdJXJGrLFi3LXiheS41MuzI3odRZUaPQmQ52hzJBI0WdIFNP9u9u1aizjX2nwaN3z7f1EezCYpEf1s0WgtBuuvoWrztAiupQGhdGUDqTwoqwITvYRbpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=z3ntu.xyz; spf=pass smtp.mailfrom=z3ntu.xyz; dkim=pass (1024-bit key) header.d=z3ntu.xyz header.i=@z3ntu.xyz header.b=e3bheGnR; arc=none smtp.client-ip=128.199.32.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=z3ntu.xyz Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=z3ntu.xyz Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=z3ntu.xyz header.i=@z3ntu.xyz header.b="e3bheGnR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=z3ntu.xyz; s=s1; t=1716573320; bh=NE3+asARG+T0s+9Kmlx2qtu/4uK3J6MB1QLPal+bElU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=e3bheGnRdMoLMHBHDKhHLoteVK3Xh7+4NP0w86XYuAGLDLLBw8H46SyfBulhucqB5 BgUGEQDgh9nkQcyITUdUOb+wfWaoEeIopVp5qPCFzLJXjwx7tOaekJHv8Q+/p0hGiT 6/N02nnwkrdP9GXWmOnDFITmKg7aq7UfcWY4aJvo= From: Luca Weiss To: Rob Herring , Krzysztof Kozlowski , ~postmarketos/upstreaming@lists.sr.ht Cc: ~postmarketos/upstreaming@lists.sr.ht, phone-devel@vger.kernel.org, Bjorn Andersson , Konrad Dybcio , Krzysztof Kozlowski , Conor Dooley , Andy Gross , linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Krzysztof Kozlowski Subject: Re: [PATCH RFC 1/2] dt-bindings: soc: qcom,smsm: Allow specifying mboxes instead of qcom,ipc Date: Fri, 24 May 2024 19:55:19 +0200 Message-ID: <4881282.LvFx2qVVIh@g550jk> In-Reply-To: References: <20240424-smsm-mbox-v1-0-555f3f442841@z3ntu.xyz> <5099926.GXAFRqVoOG@g550jk> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" On Donnerstag, 23. Mai 2024 08:19:11 MESZ Krzysztof Kozlowski wrote: > On 23/05/2024 08:16, Luca Weiss wrote: > > On Donnerstag, 23. Mai 2024 08:02:13 MESZ Krzysztof Kozlowski wrote: > >> On 22/05/2024 19:34, Luca Weiss wrote: > >>> On Mittwoch, 22. Mai 2024 08:49:43 MESZ Krzysztof Kozlowski wrote: > >>>> On 21/05/2024 22:35, Luca Weiss wrote: > >>>>> On Dienstag, 21. Mai 2024 10:58:07 MESZ Krzysztof Kozlowski wrote: > >>>>>> On 20/05/2024 17:11, Luca Weiss wrote: > >>>>>>> Hi Krzysztof > >>>>>>> > >>>>>>> Ack, sounds good. > >>>>>>> > >>>>>>> Maybe also from you, any opinion between these two binding styles? > >>>>>>> > >>>>>>> So first using index of mboxes for the numbering, where for the known > >>>>>>> usages the first element (and sometimes the 3rd - ipc-2) are empty <>. > >>>>>>> > >>>>>>> The second variant is using mbox-names to get the correct channel-mbox > >>>>>>> mapping. > >>>>>>> > >>>>>>> - qcom,ipc-1 = <&apcs 8 13>; > >>>>>>> - qcom,ipc-2 = <&apcs 8 9>; > >>>>>>> - qcom,ipc-3 = <&apcs 8 19>; > >>>>>>> + mboxes = <0>, <&apcs 13>, <&apcs 9>, <&apcs 19>; > >>>>>>> > >>>>>>> vs. > >>>>>>> > >>>>>>> - qcom,ipc-1 = <&apcs 8 13>; > >>>>>>> - qcom,ipc-2 = <&apcs 8 9>; > >>>>>>> - qcom,ipc-3 = <&apcs 8 19>; > >>>>>>> + mboxes = <&apcs 13>, <&apcs 9>, <&apcs 19>; > >>>>>>> + mbox-names = "ipc-1", "ipc-2", "ipc-3"; > >>>>>> > >>>>>> Sorry, don't get, ipc-1 is the first mailbox, so why would there be <0> > >>>>>> in first case? > >>>>> > >>>>> Actually not, ipc-0 would be permissible by the driver, used for the 0th host > >>>>> > >>>>> e.g. from: > >>>>> > >>>>> /* Iterate over all hosts to check whom wants a kick */ > >>>>> for (host = 0; host < smsm->num_hosts; host++) { > >>>>> hostp = &smsm->hosts[host]; > >>>>> > >>>>> Even though no mailbox is specified in any upstream dts for this 0th host I > >>>>> didn't want the bindings to restrict that, that's why in the first example > >>>>> there's an empty element (<0>) for the 0th smsm host > >>>>> > >>>>>> Anyway, the question is if you need to know that some > >>>>>> mailbox is missing. But then it is weird to name them "ipc-1" etc. > >>>>> > >>>>> In either case we'd just query the mbox (either by name or index) and then > >>>>> see if it's there? Not quite sure I understand the sentence.. > >>>>> Pretty sure either binding would work the same way. > >>>> > >>>> The question is: does the driver care only about having some mailboxes > >>>> or the driver cares about each specific mailbox? IOW, is skipping ipc-0 > >>>> important for the driver? > >>> > >>> There's nothing special from driver side about any mailbox. Some SoCs have > >>> a mailbox for e.g. hosts 1&2&3, some have only 1&3, and apq8064 even has > >>> 1&2&3&4. > >>> > >>> And if the driver doesn't find a mailbox for a host, it just ignores it > >>> but then of course it can't 'ring' the mailbox for that host when necessary. > >>> > >>> Not sure how much more I can add here, to be fair I barely understand what > >>> this driver is doing myself apart from the obvious. > >> > >> From what you said, it looks like it is enough to just list mailboxes, > >> e.g. for ipc-1, ipc-2 and ipc-4 (so no ipc-0 and ipc-3): > > > > No, for sure we need also the possibility to list ipc-3. > > ? You can list it, what's the problem> Maybe we're talking past each other... You asked why this wouldn't work: e.g. for ipc-1, ipc-2 and ipc-4 (so no ipc-0 and ipc-3): mboxes = <&apcs 13>, <&apcs 9>, <&apcs 19>; How would we know that the 3rd mailbox (&apcs 19) is for the 4th host (previous ipc-4)? 1. If we use mboxes with indexes we'd need to have <0> values for "smsm hosts" where we don't have a mailbox for - this is at least for the 2nd smsm host (qcom,ipc-2) for a bunch of SoCs. 2. If we use mboxes with mbox-names then we could skip that since we can directly specify which "smsm host" a given mailbox is for. My only question really is whether 1. or 2. is a better idea. Is this clearer now or still not? > > > > > And my point is that I'm not sure if any platform will ever need ipc-0, but > > the code to use that if it ever exists is there - the driver always > > tries getting an mbox (currently just syscon of course) for every host > > from 0 to n. > > > > These are the current (non-mbox-API) mboxes provided to smsm: > > > > $ git grep qcom,ipc- arch/ > > arch/arm/boot/dts/qcom/qcom-apq8064.dtsi: qcom,ipc-1 = <&l2cc 8 4>; > > arch/arm/boot/dts/qcom/qcom-apq8064.dtsi: qcom,ipc-2 = <&l2cc 8 14>; > > arch/arm/boot/dts/qcom/qcom-apq8064.dtsi: qcom,ipc-3 = <&l2cc 8 23>; > > arch/arm/boot/dts/qcom/qcom-apq8064.dtsi: qcom,ipc-4 = <&sps_sic_non_secure 0x4094 0>; > > arch/arm/boot/dts/qcom/qcom-msm8974.dtsi: qcom,ipc-1 = <&apcs 8 13>; > > arch/arm/boot/dts/qcom/qcom-msm8974.dtsi: qcom,ipc-2 = <&apcs 8 9>; > > arch/arm/boot/dts/qcom/qcom-msm8974.dtsi: qcom,ipc-3 = <&apcs 8 19>; > > arch/arm64/boot/dts/qcom/msm8916.dtsi: qcom,ipc-1 = <&apcs 8 13>; > > arch/arm64/boot/dts/qcom/msm8916.dtsi: qcom,ipc-3 = <&apcs 8 19>; > > arch/arm64/boot/dts/qcom/msm8939.dtsi: qcom,ipc-1 = <&apcs1_mbox 8 13>; > > arch/arm64/boot/dts/qcom/msm8939.dtsi: qcom,ipc-3 = <&apcs1_mbox 8 19>; > > arch/arm64/boot/dts/qcom/msm8953.dtsi: qcom,ipc-1 = <&apcs 8 13>; > > arch/arm64/boot/dts/qcom/msm8953.dtsi: qcom,ipc-3 = <&apcs 8 19>; > > arch/arm64/boot/dts/qcom/msm8976.dtsi: qcom,ipc-1 = <&apcs 8 13>; > > arch/arm64/boot/dts/qcom/msm8976.dtsi: qcom,ipc-2 = <&apcs 8 9>; > > arch/arm64/boot/dts/qcom/msm8976.dtsi: qcom,ipc-3 = <&apcs 8 19>; > > > >> > >> mboxes = <&apcs 13>, <&apcs 9>, <&apcs 19>; > > So which case is not covered? > > Best regards, > Krzysztof > >