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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 C2FCDC47409 for ; Thu, 19 Dec 2019 18:06:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A55452465E for ; Thu, 19 Dec 2019 18:06:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726880AbfLSSGe (ORCPT ); Thu, 19 Dec 2019 13:06:34 -0500 Received: from foss.arm.com ([217.140.110.172]:41654 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726836AbfLSSGe (ORCPT ); Thu, 19 Dec 2019 13:06:34 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EE13E1FB; Thu, 19 Dec 2019 10:06:32 -0800 (PST) Received: from bogus (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 199983F67D; Thu, 19 Dec 2019 10:06:30 -0800 (PST) Date: Thu, 19 Dec 2019 18:06:29 +0000 From: Sudeep Holla To: Ulf Hansson Cc: Lorenzo Pieralisi , Rob Herring , Linux PM , "Rafael J . Wysocki" , Daniel Lezcano , Mark Rutland , Lina Iyer , Vincent Guittot , Stephen Boyd , Andy Gross , Bjorn Andersson , Kevin Hilman , Linux ARM , linux-arm-msm Subject: Re: [PATCH v4 13/14] cpuidle: psci: Add support for PM domains by using genpd Message-ID: <20191219180629.GC21846@bogus> References: <20191211154343.29765-1-ulf.hansson@linaro.org> <20191211154343.29765-14-ulf.hansson@linaro.org> <20191219143427.GF20746@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Thu, Dec 19, 2019 at 04:48:39PM +0100, Ulf Hansson wrote: > On Thu, 19 Dec 2019 at 15:34, Sudeep Holla wrote: > > > > On Wed, Dec 11, 2019 at 04:43:42PM +0100, Ulf Hansson wrote: > > > When the hierarchical CPU topology layout is used in DT and the PSCI OSI > > > mode is supported by the PSCI FW, let's initialize a corresponding PM > > > domain topology by using genpd. This enables a CPU and a group of CPUs, > > > when attached to the topology, to be power-managed accordingly. > > > > > > To trigger the attempt to initialize the genpd data structures let's use a > > > subsys_initcall, which should be early enough to allow CPUs, but also other > > > devices to be attached. > > > > > > The initialization consists of parsing the PSCI OF node for the topology > > > and the "domain idle states" DT bindings. In case the idle states are > > > compatible with "domain-idle-state", the initialized genpd becomes > > > responsible of selecting an idle state for the PM domain, via assigning it > > > a genpd governor. > > > > > > Note that, a successful initialization of the genpd data structures, is > > > followed by a call to psci_set_osi_mode(), as to try to enable the OSI mode > > > in the PSCI FW. In case this fails, we fall back into a degraded mode > > > rather than bailing out and returning an error code. > > > > > > Co-developed-by: Lina Iyer > > > Signed-off-by: Lina Iyer > > > Signed-off-by: Ulf Hansson > > > --- > > > > > > Changes in v4: > > > - None. > > > > > > --- > > > drivers/cpuidle/cpuidle-psci-domain.c | 267 ++++++++++++++++++++++++++ > > > drivers/cpuidle/cpuidle-psci.c | 4 +- > > > drivers/cpuidle/cpuidle-psci.h | 5 + > > > 3 files changed, 274 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/cpuidle/cpuidle-psci-domain.c b/drivers/cpuidle/cpuidle-psci-domain.c > > > index 656ef3d59149..c2f94ba42222 100644 > > > --- a/drivers/cpuidle/cpuidle-psci-domain.c > > > +++ b/drivers/cpuidle/cpuidle-psci-domain.c > > > @@ -7,14 +7,281 @@ > > > * > > > */ > > > > > > +#define pr_fmt(fmt) "CPUidle PSCI: " fmt > > > + > > > #include > > > #include > > > #include > > > #include > > > #include > > > +#include > > > +#include > > > +#include > > > > > > #include "cpuidle-psci.h" > > > > > > +struct psci_pd_provider { > > > + struct list_head link; > > > + struct device_node *node; > > > +}; > > > + > > > +static LIST_HEAD(psci_pd_providers); > > > +static bool osi_mode_enabled; > > > + > > > +static int psci_pd_power_off(struct generic_pm_domain *pd) > > > +{ > > > + struct genpd_power_state *state = &pd->states[pd->state_idx]; > > > + u32 *pd_state; > > > + > > > + /* If we have failed to enable OSI mode, then abort power off. */ > > > + if (!osi_mode_enabled) > > > + return -EBUSY; > > > + > > > > Why is above check needed ? Shouldn't we have disable/remove pd of > > OSI is not enabled ? > > Well, failing to enable OSI should in practice not happen, while it > theoretically it could. > I won't assume that. Since it's new and not tested yet, I prefer to assume it can fail. > My approach to this has been to fall back to use a "degraded mode", > which seems quite common for these kind of situations. The degraded > mode means, we are preventing domain states from being used. > But why can't we just fail registering or remove if already added. They are useless for "degraded mode" anyways. And it will ensure that data->dev is NULL. Sorry now I see why you said it can be NULL but I would rather not leave those unused genpd in place in case of error. > More importantly, it also keeps the code registering the PM domains, a > bit simpler. > I feel it is simpler other way around especially if I am testing and seeing failures but I see genpd succeeding. That's confusing. -- Regards, Sudeep