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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT 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 E19FAC10F14 for ; Fri, 12 Apr 2019 13:58:00 +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 B4122206BA for ; Fri, 12 Apr 2019 13:58:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="udHLn5oE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B4122206BA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com 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=NBWExzHa8anxwrpYp/U0a+DbUyKsRIoUCopFJlbOnHg=; b=udHLn5oESJJ6Sx KDZqUucybhm3mGkp012yuHc8JxUrgtSg2234ifYgh9iyIeXot7UAHClIblrtmpiIcD4ONZZr20ARH CXNdN3khEvJo5G9bT7TSe+U/y9ieZpFjOWEfcLuzExyOPzMCQ/Kpq1KajSQ6wTuM8kNviiatc+ttD lDOawtmJMVw6WHIRpMvMrAdc5YCjEipo777Pk5FCXzZj/lakqO5r+xe8VWNU5mRKv9UoxG/0DYO1L 4aerpiBNENvV6mDEcaiDH1blUE7uVF5Cfd2lkxixSnwdmkA+XLld2CvxpsGq5/3H84ENyQWu8+meI DlAHWaRr3qurlnMRAcfg==; 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 1hEwgk-0007rg-Cy; Fri, 12 Apr 2019 13:57:54 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hEwgh-0007rN-BT for linux-arm-kernel@lists.infradead.org; Fri, 12 Apr 2019 13:57:52 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D0943374; Fri, 12 Apr 2019 06:57:50 -0700 (PDT) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B96953F557; Fri, 12 Apr 2019 06:57:49 -0700 (PDT) Date: Fri, 12 Apr 2019 14:57:47 +0100 From: Sudeep Holla To: Florian Fainelli Subject: Re: Couple of questions on SCMI sensor protocol and Linux implementation Message-ID: <20190412135747.GC23351@e107155-lin> References: <1902f151-7ddd-6b4b-4135-a2affe20c009@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1902f151-7ddd-6b4b-4135-a2affe20c009@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190412_065751_399659_DD7CB6C7 X-CRM114-Status: GOOD ( 18.58 ) 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: linux-hwmon@vger.kernel.org, Guenter Roeck , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" , Sudeep Holla 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 On Tue, Apr 02, 2019 at 08:22:58PM -0700, Florian Fainelli wrote: > Hi Sudeep, > > There are a couple of things on which I would appreciate your feedback > regarding the Linux SCMI sensor protocol: > > 1) The Linux SCMI implementation has all the nuts and bolts to allow > configuring trip points, but the hwmon subsystem through the use of > hwmon_thermal_add_sensor() API does not actually make use of that > capability. Would it be a big stretch to use the hwmon_ops::write > function to get to support that feature? As a concept, it sounds good. Though I am not sure if write API semantics match with what we want here with trip point configuration. > The other thing that puzzles me > is that there does not appear to be provision in the SCMI sensor > protocol to describe thermal zones, so I assume that people still have > to provide supplemental data through Device Tree for > devm_thermal_zone_of_sensor_register() to pick up the thermal zones > definitions? > Yes, I tend to agree. When SCMI v1.0 was designed we were not sure if we can incorporate thermal zones into the specification without losing the flexibility that vendors have today with DT. If you think we should update the specification for this, can you send me brief summary so that the discussion on the specification side can be kicked off. > 2) Support for regulators through SCMI > > I work with a device where the regulators can only be controlled via a > dedicated piece of HW which is accessible through SCMI from the Linux > side. Do you think there is value in coming up with a scmi-regulator.c > driver that makes use of the sensor protocol for discovering and > reporting regulators or would that be something that belongs more to the > power domain protocol? > Controlling regulators directly from OSPM/Linux via SCMI was intentionally not added to the specification. One of the issues SCMI wanted to address is clockscrew[1] kind of security attacks exploiting direct regulator control. -- Regards, Sudeep [1] https://www.usenix.org/system/files/conference/usenixsecurity17/sec17-tang.pdf _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel