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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 6C394C31E45 for ; Thu, 13 Jun 2019 21:37:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48A75208CA for ; Thu, 13 Jun 2019 21:37:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727075AbfFMVhe (ORCPT ); Thu, 13 Jun 2019 17:37:34 -0400 Received: from cloudserver094114.home.pl ([79.96.170.134]:49424 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725747AbfFMVhe (ORCPT ); Thu, 13 Jun 2019 17:37:34 -0400 Received: from 79.184.253.190.ipv4.supernova.orange.pl (79.184.253.190) (HELO kreacher.localnet) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.267) id 480796b137926e4f; Thu, 13 Jun 2019 23:37:31 +0200 From: "Rafael J. Wysocki" To: Shaunak Saha Cc: linux-acpi@vger.kernel.org, mario_limonciello@dell.com Subject: Re: drivers/acpi: Change the lpit function call flow Date: Thu, 13 Jun 2019 23:37:30 +0200 Message-ID: <2151762.asltZFE8WJ@kreacher> In-Reply-To: <20190526202750.4614-1-shaunak.saha@intel.com> References: <20190526202750.4614-1-shaunak.saha@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Sunday, May 26, 2019 10:27:50 PM CEST Shaunak Saha wrote: > In the present implementation sleep function was getting called in > acpi_s2idle_prepare and as all the devices may not have suspended > at that stage e.g. if we are telling ec about the S0ix then calling early > can cause ec reply wrongly interpreted as spurious wake events. > Here we call it at much later stage in acpi_s2idle_sync. As per the > specification the entry _DSM function may be invoked when the OS state has > reached sufficient criteria for processor idle state entry matching > Entry Trigger defined in LPIT to be interpreted as a request for the > platform to enter a Low Power S0 Idle (LPI) state. Here we are checking if > the we reached the minimum D-State defined in the constraint function of > the LPIT _DSM method before calling the sleep entry function. Also not > checking for constraint in acpi_s2idle_wake anymore and also changed the > acpi info loglevel to debug in lpi_check_constraint. This patch does three different things, two of which are questionable and one is done incorrectly. First off, aborting system suspend because S0ix constraints are not met is a non-starter. The kernel really cannot refuse to suspend the system for that reason (and diagnostics can be done after resume anyway). Second, according to my knowledge, it is not a bug to invoke the ACPI_LPS0_ENTRY _DSM when the constraints are not met. Do you actually know about any platforms where that may cause real problems to occur? Finally, it is too late to invoke that _DSM from acpi_s2idle_sync(), because that is called after leaving S0ix and resuming some devices. I can believe the claim that invoking the ACPI_LPS0_ENTRY _DSM in acpi_s2idle_prepare() may be too early and it may confuse the EC, say, but I'm not sure why the ACPI_LPS0_SCREEN_OFF _DSM would be affected by that too. So overall, the patch below may actually work, but not the $subject one (if evaluating the ACPI_LPS0_ENTRY _DSM when the constraints are not met is *really* problematic, it may be necessary to add the check for that on top of it). --- drivers/acpi/sleep.c | 13 +++++++++---- include/linux/suspend.h | 1 + kernel/power/suspend.c | 8 ++++++-- 3 files changed, 16 insertions(+), 6 deletions(-) Index: linux-pm/drivers/acpi/sleep.c =================================================================== --- linux-pm.orig/drivers/acpi/sleep.c +++ linux-pm/drivers/acpi/sleep.c @@ -967,8 +967,6 @@ static int acpi_s2idle_prepare(void) { if (lps0_device_handle) { acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_OFF); - acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY); - acpi_ec_set_gpe_wake_mask(ACPI_GPE_ENABLE); } @@ -983,6 +981,12 @@ static int acpi_s2idle_prepare(void) return 0; } +static void acpi_s2idle_sleep(void) +{ + if (lps0_device_handle) + acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY); +} + static void acpi_s2idle_wake(void) { if (!lps0_device_handle) @@ -1007,6 +1011,8 @@ static void acpi_s2idle_wake(void) */ acpi_ec_dispatch_gpe(); } + + acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT); } static void acpi_s2idle_sync(void) @@ -1034,8 +1040,6 @@ static void acpi_s2idle_restore(void) if (lps0_device_handle) { acpi_ec_set_gpe_wake_mask(ACPI_GPE_DISABLE); - - acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT); acpi_sleep_run_lps0_dsm(ACPI_LPS0_SCREEN_ON); } } @@ -1049,6 +1053,7 @@ static void acpi_s2idle_end(void) static const struct platform_s2idle_ops acpi_s2idle_ops = { .begin = acpi_s2idle_begin, .prepare = acpi_s2idle_prepare, + .sleep = acpi_s2idle_sleep, .wake = acpi_s2idle_wake, .sync = acpi_s2idle_sync, .restore = acpi_s2idle_restore, Index: linux-pm/include/linux/suspend.h =================================================================== --- linux-pm.orig/include/linux/suspend.h +++ linux-pm/include/linux/suspend.h @@ -190,6 +190,7 @@ struct platform_suspend_ops { struct platform_s2idle_ops { int (*begin)(void); int (*prepare)(void); + void (*sleep)(void); void (*wake)(void); void (*sync)(void); void (*restore)(void); Index: linux-pm/kernel/power/suspend.c =================================================================== --- linux-pm.orig/kernel/power/suspend.c +++ linux-pm/kernel/power/suspend.c @@ -136,10 +136,14 @@ static void s2idle_loop(void) * so prevent them from terminating the loop right away. */ error = dpm_noirq_suspend_devices(PMSG_SUSPEND); - if (!error) + if (!error) { + if (s2idle_ops && s2idle_ops->sleep) + s2idle_ops->sleep(); + s2idle_enter(); - else if (error == -EBUSY && pm_wakeup_pending()) + } else if (error == -EBUSY && pm_wakeup_pending()) { error = 0; + } if (!error && s2idle_ops && s2idle_ops->wake) s2idle_ops->wake();