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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 336A4C433E1 for ; Mon, 17 Aug 2020 17:33:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 03AA12063A for ; Mon, 17 Aug 2020 17:33:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="oG2E2fsP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730680AbgHQRdx (ORCPT ); Mon, 17 Aug 2020 13:33:53 -0400 Received: from mail29.static.mailgun.info ([104.130.122.29]:42671 "EHLO mail29.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389020AbgHQQuW (ORCPT ); Mon, 17 Aug 2020 12:50:22 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1597683021; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=GhyGcHtsJNSaWRlw4MXPmZ9Q7h5P+6kgTtX8VYoSKpY=; b=oG2E2fsPlOwWTfzzRyTRsU3HoA04Fk1ZdbyUSouafeqrGdiWxZphQ0Pu5GT39oUnC+LnwFzl BkJYXD/6Wqs+frqWc8morJVqkhTPUXkQ2QO2VQpOkgbiJ4z6ETz6iixXRqgdnmldRzxoMWNk V1yJ9yAYMYrt5ZPnWUmkAckQ3hU= X-Mailgun-Sending-Ip: 104.130.122.29 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n02.prod.us-east-1.postgun.com with SMTP id 5f3ab512f2b697637a950740 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Mon, 17 Aug 2020 16:49:22 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 9E919C433AF; Mon, 17 Aug 2020 16:49:21 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: sibis) by smtp.codeaurora.org (Postfix) with ESMTPSA id 2A69FC43391; Mon, 17 Aug 2020 16:49:20 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 17 Aug 2020 22:19:20 +0530 From: Sibi Sankar To: Ulf Hansson Cc: Bjorn Andersson , "Rafael J. Wysocki" , Andy Gross , Linux Kernel Mailing List , linux-arm-msm , Linux PM , Greg Kroah-Hartman , Pavel Machek , Len Brown , Rajendra Nayak , Doug Anderson , linux-kernel-owner@vger.kernel.org, Kevin Hilman , linux-arm-msm-owner@vger.kernel.org Subject: Re: [PATCH 1/2] PM / Domains: Add GENPD_FLAG_SUSPEND_ON flag In-Reply-To: References: <20200811190252.10559-1-sibis@codeaurora.org> <1ba3e4d703dd0a52547d63fa014451eb@codeaurora.org> <1ca666c336ebee569a429e729d5ae547@codeaurora.org> Message-ID: <33169e221707a2456397e478b275cfa9@codeaurora.org> X-Sender: sibis@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-08-17 14:14, Ulf Hansson wrote: > On Thu, 13 Aug 2020 at 19:26, Sibi Sankar wrote: >> >> On 2020-08-13 18:04, Ulf Hansson wrote: >> > On Wed, 12 Aug 2020 at 19:03, Sibi Sankar wrote: >> >> >> >> Uffe, >> >> Thanks for taking time to review the >> >> series! >> >> >> >> On 2020-08-12 15:15, Ulf Hansson wrote: >> >> > On Tue, 11 Aug 2020 at 21:03, Sibi Sankar wrote: >> >> >> >> >> >> This is for power domains which needs to stay powered on for suspend >> >> >> but can be powered on/off as part of runtime PM. This flag is aimed at >> >> >> power domains coupled to remote processors which enter suspend states >> >> >> independent to that of the application processor. Such power domains >> >> >> are turned off only on remote processor crash/shutdown. >> >> > >> >> > As Kevin also requested, please elaborate more on the use case. >> >> > >> >> > Why exactly must the PM domain stay powered on during system suspend? >> >> > Is there a wakeup configured that needs to be managed - or is there a >> >> > co-processor/FW behaviour that needs to be obeyed to? >> >> >> >> Yes this is a co-processor behavior that >> >> needs to be obeyed. Specifically application >> >> processor notifies the Always on Subsystem >> >> (AOSS) that a particular co-processor is up >> >> using the power domains exposed by AOSS QMP >> >> driver. AOSS uses this information to wait >> >> for the co-processors to suspend before >> >> starting its sleep sequence. The application >> >> processor powers off these power domains only >> >> if the co-processor has crashed or powered >> >> off. >> > >> > Thanks for clarifying! >> > >> > Although, can you please elaborate a bit more on the actual use case? >> > What are the typical co-processor and what drivers are involved in >> > managing it? >> >> The co-processors using the power domains >> exposed by qcom_aoss driver are modem, >> audio dsp, compute dsp managed using >> qcom_q6v5_mss and qcom_q6v5_pas driver. >> >> > >> > As you may know, runtime PM becomes disabled during system suspend of >> > a device. Which means, if the driver tries to power off the >> > coprocessor (via calling pm_runtime_put() for example), somewhere in >> > the system suspend phase of the corresponding device, its attached PM >> > domain stays powered on when managed by genpd. >> >> The drivers aren't really expected >> do anything during suspend/resume >> pretty much because the co-processors >> enter low-power modes independent to >> that of the application processor. On >> co-processor crash the remoteproc core >> does a pm_stay_awake followed by a >> pm_relax after crash recovery. > > Okay, thanks again for clarifying. You have convinced me about the > need for a new flag to cope with these use cases. > > Would you mind updating the commit message with some of the > information you just provided? > > Additionally, to make it clear that the flag should be used to keep > the PM domain powered on during system suspend, but only if it's > already powered on - please rename the flag to GENPD_FLAG_NO_SUSPEND, > and update the corresponding description of it in the header file. Thanks, naming it ^^ makes more sense :) https://lore.kernel.org/lkml/340a7aafcf0301ff3158a4e211992041@codeaurora.org/ Also we wouldn't want to power on runtime suspended power domains with the NO_SUSPEND flag set, on resume as explained ^^. Do you agree with that as well? > > [...] > > Kind regards > Uffe -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.