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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 610A1C48BF6 for ; Thu, 29 Feb 2024 09:45:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=peyYiiJNgy/pr5Xh0v9CmRUMIlzvTgSc432/YpP2mkI=; b=XgpCjYr8rtiQNmjnXML3CNIjk4 A9v0oDduPPV2IcVzCfW5/jDfV6FjNm9eVTJPzanJylEVOr6E5Z2ABWxM0uF88tcxyG0jqceUZh2bH mRHrQvXpr1c3sFZ4fBY/7sOjBFOP31yma/67iwV8kmXCkyH/Z3hTDVgbvMMFq1H+YC5oriROtJdjT 9DRnYgwiWBbyf+kYL4+O1dEpprvOP/Z389VJ1LfA+FvER7KuX+6ha/ZTZYKhoE0hchZ8ad9F2/tU8 0uld8JFGiPH/nrd/K54z7LZkIdDVDAv1bxAEbihojpPRmaEhequ9qymXwkPWqqDHFzFwiq65C8/d8 JWucB7qQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rfcyr-0000000CzcK-3J6k; Thu, 29 Feb 2024 09:45:33 +0000 Received: from madrid.collaboradmins.com ([2a00:1098:ed:100::25]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rfcyo-0000000Cza5-1OKT; Thu, 29 Feb 2024 09:45:31 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1709199928; bh=zqMod5Dpmo25ZYJnsrKD9ta8Mkuv6yxXbpPE124uuWg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=cGGUw0GnTQlL8WhUt9CYdUBIGh5WzXoZi4F6acKTJ/nfgKY0bGsEOMGPt+4hfVPrz vNpEJT8waAK2cuNo6R8RcTti5lm4I6qYEL0bVw8d0g6uQ+P4l/w0ALBQy5DRjnWhtC /v4VOleLj0QalfQK4cWa6ebsZS7R8HLJtNoxVUE7QTpP5z7S25zZg48tceTKSD49pZ G8M+V6D0VhHTRqQBL4U1ecuV7CJQjRMU/TSrYsnDxCgaRoHo+gWArm3BptRnP9R1dM XNNTHfu+mlgCxmD8M9lOyNVNx2IOLPr2gLsJXJUoxPfBWa/6YU1AH9zYr7NsFRpjiI qnCJozDOS5mpg== Received: from [100.113.186.2] (cola.collaboradmins.com [195.201.22.229]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: kholk11) by madrid.collaboradmins.com (Postfix) with ESMTPSA id 335B53780F7F; Thu, 29 Feb 2024 09:45:28 +0000 (UTC) Message-ID: Date: Thu, 29 Feb 2024 10:45:27 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/2] clk: mediatek: Introduce need_pm_runtime to mtk_clk_desc Content-Language: en-US To: Chen-Yu Tsai Cc: Pin-yen Lin , Michael Turquette , Stephen Boyd , Matthias Brugger , Weiyi Lu , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org References: <20240108081834.408403-1-treapking@chromium.org> From: AngeloGioacchino Del Regno In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240229_014530_588870_F4F66893 X-CRM114-Status: GOOD ( 39.02 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org Il 29/02/24 08:17, Chen-Yu Tsai ha scritto: > On Mon, Feb 26, 2024 at 7:16 PM AngeloGioacchino Del Regno > wrote: >> >> Il 23/02/24 05:27, Chen-Yu Tsai ha scritto: >>> On Mon, Jan 8, 2024 at 4:18 PM Pin-yen Lin wrote: >>>> >>>> Introduce a new need_pm_runtime variable to mtk_clk_desc to indicate >>>> this clock controller needs runtime PM for its operations. >>>> Also do a runtime PM get on the clock controller during the >>>> probing stage to workaround a possible deadlock. >>>> >>>> Signed-off-by: Pin-yen Lin >>> >>> Reviewed-by: Chen-Yu Tsai >>> >>> The patch itself looks fine. >>> >>> Besides the MT8183 MFG clock issues, we do actually need this for the >>> MT8192 ADSP clock. Its power domain is not enabled by default. >>> >> >> ...but on MT8195 the ADSP clock works - because the ADSP node exists. > > That's an indirect dependency that should not be relied on. Say the clock > driver probed but the ADSP hasn't, and you try to read out the current > status. What would happen? > > - Read out works fine, because the power domain is default on, and hasn't > been turned off by late cleanup > - Read out is bogus (but you can't tell) > - Read out hangs. > > The third is what happens on MT8192. There's still some issues on that > front, as even after I applied the ADSP power domain patches from MediaTek, > the readout was still hanging. > That MT8192 lockup story is getting crazy in my head... anyway, besides that, I get the point - I was somehow ignoring the fact that kernel modules do exist. Eh, sorry about that :-) >> This poses a question: should we make clock controllers depend on power domains, >> or should we keep everything powered off (hence clocks down - no power consumption) >> *unless* the user exists? > > That's a policy discussion separate from actual hardware dependencies. > *If* the clock controller needs the power domain to be active for the > registers to be accessed, the clock controller *must* have a direct > dependency on the power domain. > I admit I should've worded that better. "should we make clock controllers depend on power domains" was actually implying "IF those need one" :-) I really wonder if - at this point - it's simply a better idea to not restrict the call to devm_pm_runtime_enable/resume_and_get to `need_runtime_pm == true`. Do we really need to exclude that on other clock controllers that don't have any power domain dependency? Any side effect? Saying this because if we can avoid yet another per-SoC flag I'm really happy, as readability is also impacted and besides - if we ever find out that one of those need a power domain in the future, we'll need just one commit and just only in the devicetree, instead of enabling a flag in driver X as well as that, avoiding some (potentially unnecessary) noise... I guess. P.S.: I just noticed that the return value for the devm_pm_runtime_enable() call is not being checked! ....... In short.... Chen-Yu, at this point, do you have any reason why we wouldn't be able and/or it wouldn't be a good idea to just avoid adding the `need_runtime_pm` flag (meaning that we perform pm_runtime calls for all clock drivers unconditionally)? If this is about longer boot time, I don't think that it's going to be more than a millisecond or two, so that should be completely ignorable. Can you please do a test for that, or should I? Cheers Angelo >> For the second one, this means that the *device* gets the power domain (adsp), and >> not the clock controller (which clocks are effectively useless if there's no user). > > No. See my previous paragraph. > > ChenYu > >> Angelo >> >>>> --- >>>> >>>> Changes in v3: >>>> - Update the commit message and the comments before runtime PM call >>>> >>>> Changes in v2: >>>> - Fix the order of error handling >>>> - Update the commit message and add a comment before the runtime PM call >>>> >>>> drivers/clk/mediatek/clk-mtk.c | 19 +++++++++++++++++++ >>>> drivers/clk/mediatek/clk-mtk.h | 2 ++ >>>> 2 files changed, 21 insertions(+) >>>> >>>> diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c >>>> index 2e55368dc4d8..ba1d1c495bc2 100644 >>>> --- a/drivers/clk/mediatek/clk-mtk.c >>>> +++ b/drivers/clk/mediatek/clk-mtk.c >>>> @@ -13,6 +13,7 @@ >>>> #include >>>> #include >>>> #include >>>> +#include >>>> #include >>>> >>>> #include "clk-mtk.h" >>>> @@ -494,6 +495,18 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev, >>>> return IS_ERR(base) ? PTR_ERR(base) : -ENOMEM; >>>> } >>>> >>>> + >>>> + if (mcd->need_runtime_pm) { >>>> + devm_pm_runtime_enable(&pdev->dev); >>>> + /* >>>> + * Do a pm_runtime_resume_and_get() to workaround a possible >>>> + * deadlock between clk_register() and the genpd framework. >>>> + */ >>>> + r = pm_runtime_resume_and_get(&pdev->dev); >>>> + if (r) >>>> + return r; >>>> + } >>>> + >>>> /* Calculate how many clk_hw_onecell_data entries to allocate */ >>>> num_clks = mcd->num_clks + mcd->num_composite_clks; >>>> num_clks += mcd->num_fixed_clks + mcd->num_factor_clks; >>>> @@ -574,6 +587,9 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev, >>>> goto unregister_clks; >>>> } >>>> >>>> + if (mcd->need_runtime_pm) >>>> + pm_runtime_put(&pdev->dev); >>>> + >>>> return r; >>>> >>>> unregister_clks: >>>> @@ -604,6 +620,9 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev, >>>> free_base: >>>> if (mcd->shared_io && base) >>>> iounmap(base); >>>> + >>>> + if (mcd->need_runtime_pm) >>>> + pm_runtime_put(&pdev->dev); >>>> return r; >>>> } >>>> >>>> diff --git a/drivers/clk/mediatek/clk-mtk.h b/drivers/clk/mediatek/clk-mtk.h >>>> index 22096501a60a..c17fe1c2d732 100644 >>>> --- a/drivers/clk/mediatek/clk-mtk.h >>>> +++ b/drivers/clk/mediatek/clk-mtk.h >>>> @@ -237,6 +237,8 @@ struct mtk_clk_desc { >>>> >>>> int (*clk_notifier_func)(struct device *dev, struct clk *clk); >>>> unsigned int mfg_clk_idx; >>>> + >>>> + bool need_runtime_pm; >>>> }; >>>> >>>> int mtk_clk_pdev_probe(struct platform_device *pdev); >>>> -- >>>> 2.43.0.472.g3155946c3a-goog >>>> >> >> >>