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=-3.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_NEOMUTT 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 689B2C04AAC for ; Mon, 20 May 2019 10:52:03 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 3BA3A2081C for ; Mon, 20 May 2019 10:52:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="K8BF7dQS"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="kYY51UqL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3BA3A2081C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=s9J16mXTvA5P06e34VwnUK5HD3g4KQetOLO9K/ELy2A=; b=K8BF7dQStZuZMO MUqJUosQk9gm8JmqyLYVWHGzk20CH/EkFO7hC/q81yMZ/gYMn64u16CskaRUermHku8EqNqoHbyPa gU+kcA0kgM34UybHqCcUsMSTbsw23A3U+vtstvGmUrZ6NKacCPpg5R2H0Mfl3uNejOGYAEkzPgVJH 4L8QxWivb0BnWxwEPyzwSt4MnSiq8nAOgMywQjohOziWLp7UckzgDIFkGXA9pRXyQVPPUGmj1tlg2 Op11k84oRwMw9FJ2byPhfCwxwoMeYWpW37myX1MsZ3Y0+lR1zJzRCUXwzvL5q1cGs10DvYn8UvupK cHR9d9oxSEHJNwIrDrAw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hSfte-0003f6-Sh; Mon, 20 May 2019 10:51:58 +0000 Received: from mail-pl1-x644.google.com ([2607:f8b0:4864:20::644]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hSftb-0003eR-RK for linux-arm-kernel@lists.infradead.org; Mon, 20 May 2019 10:51:57 +0000 Received: by mail-pl1-x644.google.com with SMTP id x15so6545601pln.9 for ; Mon, 20 May 2019 03:51:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=1YuRtghB95O7LhcsLf1/GyzlG0H9oHKpVmg43qxycAc=; b=kYY51UqLfQVqkc2pUGOEqHYiVJK7aLiK83xI/QmKPQ83rVUHjubs4HhY3WgnjPV8Ph +p6tCG9P+dJnHcchn3HiDctSF0yQA26bk8LSB219E644Gsm0Z1FLqUnsS3+r6pJNU7JM F9fLagHSp3Mz6H1zX6oNBvGJ6baL05JXajQShS4uasI188DbB4upGMpFgPkkW+o5f/bL ZE36aahLuXDGd9PJjztiqIChzQIpcJ3YH/cNwgrxJTR7413qQpHk/qUWWIKNe90WjxM9 DRjIBj6m38yHeJnptCfjNj2CpXQpeb1y+/vPkFdyv5gLFdczZtBRPIChvp1j2Pp2eUc4 ZEUw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=1YuRtghB95O7LhcsLf1/GyzlG0H9oHKpVmg43qxycAc=; b=AO9/5rHgSzwi+PDYWTXxLZTZLXQ6kIZ0fr9kKwWFnYTvmg50vgV+3gLO46jvDrn+UZ IhFbvsXAyP4u10AWCSHAFBrbuHkHs74zRI4kbuNXPVjBOb7KoHksTqIursbeDJNWiTu7 G1qfrbVMMcoOCKmPZ6yyN+6QJ2z13xZo3OVcmdCZ61hViT8wCRTEVeC6UhWfSJRTVa7r jhjKtVgOk8LJ2KK8fUxQKj+oNmtISDCVUmtV9ZmdFBeDDa2t5sqPB/9wrDwCsroMPbkh 0o1fNelBoKQ+gj+9aeLXCZK9nUO/QLsJxZpgMidDRMxGYLe070V/b17s8FI2p2wJSFDH lIqw== X-Gm-Message-State: APjAAAWFrOtPK+gMZ4H4WjlBPiEMuKlX1BSlWOBiWwfeH83CBwOBKLSX kj6A4+OI+erKn4o6Iam3MLPpLQ== X-Google-Smtp-Source: APXvYqx2xIC25FoDnT5f3U0WxisE/vb00p1qHkPCPrdQV39EMhcy4uT+6FeiH4ZP+MSjumuKX4Eyww== X-Received: by 2002:a17:902:f20b:: with SMTP id gn11mr75087490plb.126.1558349515329; Mon, 20 May 2019 03:51:55 -0700 (PDT) Received: from localhost ([122.172.118.99]) by smtp.gmail.com with ESMTPSA id k9sm20248370pfa.180.2019.05.20.03.51.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 May 2019 03:51:54 -0700 (PDT) Date: Mon, 20 May 2019 16:21:53 +0530 From: Viresh Kumar To: Nicolas Saenz Julienne Subject: Re: [RFC v2 0/5] cpufreq support for the Raspberry Pi Message-ID: <20190520105153.ftlnjx7ocr2qkxhd@vireshk-i7> References: <20190520104708.11980-1-nsaenzjulienne@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190520104708.11980-1-nsaenzjulienne@suse.de> User-Agent: NeoMutt/20180716-391-311a52 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190520_035155_888130_1607D423 X-CRM114-Status: GOOD ( 22.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: stefan.wahren@i2se.com, devicetree@vger.kernel.org, f.fainelli@gmail.com, linux-pm@vger.kernel.org, sboyd@kernel.org, mturquette@baylibre.com, ptesarik@suse.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, eric@anholt.net, bcm-kernel-feedback-list@broadcom.com, linux-rpi-kernel@lists.infradead.org, ssuloev@orpaltech.com, linux-clk@vger.kernel.org, mbrugger@suse.de, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Archived-At: List-Archive: On 20-05-19, 12:47, Nicolas Saenz Julienne wrote: > Hi all, > as some of you may recall I've been spending some time looking into > providing 'cpufreq' support for the Raspberry Pi platform[1]. I think > I'm close to something workable, so I'd love for you to comment on it. > > There has been some design changes since the last version. Namely the > fact that I now make sure *only* the CPU frequency is updated. The > firmware API we use has two modes, with or without turbo. Enabling turbo > implies not only scaling the CPU clock but also the VPU and other > peripheral related clocks. This is problematic as some of them are not > prepared for this kind frequency changes. I spent some time adapting the > peripheral drivers, but the result was disappointing as they poorly > support live frequency changes (which most other chips accept, think for > instance I2C and clock stretching) but also turned out hard to integrate > into the kernel. As we were planning to use 'clk_notifiers' which turns > out not to be such a good idea as it's prone to deadlocks and not > recommended by the clock maintainers[2]. It's also worth mentioning that > the foundation kernel doesn't support VPU frequency scaling either. > > With this in mind, and as suggested by clock maintainers[2], I've > decided to integrate the firmware clock interface into the bcm2835 clock > driver. This, in my opinion, provides the least friction with the > firmware and lets us write very simple and portable higher level > drivers. As I did with the 'cpufreq' driver which simply queries the max > and min frequencies available, which are configurable in the firmware, > to then trigger the generic 'cpufreq-dt'. > > In the future we could further integrate other firmware dependent clocks > into the main driver. For instance to be able to scale the VPU clock, > which should be operated through a 'devfreq' driver. > > This was tested on a RPi3b+ and if the series is well received I'll test > it further on all platforms I own. Please always supply version history on what has changed from V1. And why do you keep sending it as RFC ? Just keep the default PATCH thing, the patches are in good shape I would say. -- viresh _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel