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=-4.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, T_DKIMWL_WL_HIGH autolearn=ham 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 F16DFC04AB5 for ; Thu, 6 Jun 2019 18:23:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CDEA72089E for ; Thu, 6 Jun 2019 18:23:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559845416; bh=uBH628PpMIXdWXns/puGxfoIumvbSwI35XKwjmJuMPI=; h=In-Reply-To:References:To:From:Subject:Cc:Date:List-ID:From; b=RslRlsW8IcDJrMKSMJaebEtuBBd0DNxbGOWqe/WnCSVxifXiUcr1lWZtCyc7o26jX tVbESHnzPDv1L5DvVz9FwgJP1o14lIPf+oqboX5WHDbP4Xcy6ygsWNcRaOIzhFki1y 4urP691eTNc42T9Uchk69GnjZEnGP2gRU7e679is= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730576AbfFFSXg (ORCPT ); Thu, 6 Jun 2019 14:23:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:59108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729519AbfFFSXg (ORCPT ); Thu, 6 Jun 2019 14:23:36 -0400 Received: from kernel.org (unknown [104.132.0.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1D15F20872; Thu, 6 Jun 2019 18:23:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559845415; bh=uBH628PpMIXdWXns/puGxfoIumvbSwI35XKwjmJuMPI=; h=In-Reply-To:References:To:From:Subject:Cc:Date:From; b=pAMvr43M86UT2rG55Cqly5Tn4+ejdwFYUmkTyDUgTVX9PnwfMuUi1X7XfcKe8szEi rfDD1yuAV0bpfcGHhdnnBbjlfwJP2P4eXkiesvVyWpJirycBn8/bBrSBrdTLER4ReV hj49dvU7/xcvBAVugk2nadOfy48zsFnvITZS1pUU= Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable In-Reply-To: <153579ddd7e6bd1e5c860a7a01115e47c78a1442.camel@suse.de> References: <20190606142255.29454-1-nsaenzjulienne@suse.de> <20190606142255.29454-5-nsaenzjulienne@suse.de> <20190606170949.4A46720652@mail.kernel.org> <20190606173609.2C3952083D@mail.kernel.org> <153579ddd7e6bd1e5c860a7a01115e47c78a1442.camel@suse.de> To: "Rafael J. Wysocki" , Nicolas Saenz Julienne , Viresh Kumar , stefan.wahren@i2se.com From: Stephen Boyd Subject: Re: [PATCH v2 4/7] cpufreq: add driver for Raspbery Pi Cc: linux-arm-kernel@lists.infradead.org, f.fainelli@gmail.com, ptesarik@suse.com, mturquette@baylibre.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, eric@anholt.net, bcm-kernel-feedback-list@broadcom.com, linux-rpi-kernel@lists.infradead.org, linux-clk@vger.kernel.org, mbrugger@suse.de, ssuloev@orpaltech.com User-Agent: alot/0.8.1 Date: Thu, 06 Jun 2019 11:23:34 -0700 Message-Id: <20190606182335.1D15F20872@mail.kernel.org> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Quoting Nicolas Saenz Julienne (2019-06-06 11:10:04) > On Thu, 2019-06-06 at 10:36 -0700, Stephen Boyd wrote: > > Quoting Nicolas Saenz Julienne (2019-06-06 10:22:16) > > > Hi Stephen, > > > Thanks for the review. > > >=20 > > > On Thu, 2019-06-06 at 10:09 -0700, Stephen Boyd wrote: > > > > Quoting Nicolas Saenz Julienne (2019-06-06 07:22:56) > > > > > diff --git a/drivers/cpufreq/raspberrypi-cpufreq.c > > > > > b/drivers/cpufreq/raspberrypi-cpufreq.c > > > > > new file mode 100644 > > > > > index 000000000000..99b59d5a50aa > > > > > --- /dev/null > > > > > +++ b/drivers/cpufreq/raspberrypi-cpufreq.c > > > > [...] > > > > > + > > > > > +/* > > > > > + * Since the driver depends on clk-raspberrypi, which may return > > > > > EPROBE_DEFER, > > > > > + * all the activity is performed in the probe, which may be defe= red as > > > > > well. > > > > > + */ > > > > > +static struct platform_driver raspberrypi_cpufreq_driver =3D { > > > > > + .driver =3D { > > > > > + .name =3D "raspberrypi-cpufreq", > > > > > + }, > > > > > + .probe =3D raspberrypi_cpufreq_probe, > > > > > + .remove =3D raspberrypi_cpufreq_remove, > > > > > +}; > > > > > +module_platform_driver(raspberrypi_cpufreq_driver); > > > >=20 > > > > How does this driver probe? Do you have a node in DT named > > > > raspberrypi-cpufreq that matches and probes this? I would think this > > > > would follow the drivers/cpufreq/cpufreq-dt-platdev.c design where = it's > > > > an initcall that probes the board compatible string. > > > >=20 > > > > Or, if it depends on clk-raspberrypi probing, maybe it could create= the > > > > platform device in that drivers probe function. > > >=20 > > > Well you just reviewed that patch :) > >=20 > > Ok. So what's your plan? >=20 > So as discussed previously with the RPi mantainers, they preferred for the > platform device for raspberrypi-clk to be created by the firmware interfa= ce > driver. IIRC Stefan said it was more flexible and the approach used with = RPi's > hwmon driver already. Also, it's not really clear whether this driver rea= lly > fits the device tree as it wouldn't be describing hardware. >=20 > As far as raspberrypi-cpufreq is concerned the max and min frequencies are > configurable in the firmware. So we can't really integrate cpufreq into t= he > device tree as we need to create the opp table dynamically. Hence the ded= icated > driver. On top of that the CPU might not have a clock during the init pro= cess, > as both the firmware interface and raspberrypi-clk can be compiled as mod= ules. > So I decided the simplest solution was to create the raspberrypi-cpufreq > platform device at the end of raspberrypi-clk's probe. >=20 > Once raspberrypi-cpufreq is loaded it queries the min/max frequencies, > populates the CPU's opp table and creates an instance of cpufreq-dt. Which > finally can operate, without the need of any dt info, as opp tables are > populated and CPUs have a clock. >=20 > I hope this makes it a little more clear :). >=20 Yes, thanks. I see that largely follows the commit description so it looks OK to me.