From patchwork Tue Jul 14 11:41:04 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geert Uytterhoeven X-Patchwork-Id: 6786581 X-Patchwork-Delegate: geert@linux-m68k.org Return-Path: X-Original-To: patchwork-linux-sh@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 43490C05AC for ; Tue, 14 Jul 2015 11:41:27 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 51B42206D4 for ; Tue, 14 Jul 2015 11:41:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5ADE9205EA for ; Tue, 14 Jul 2015 11:41:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752066AbbGNLlL (ORCPT ); Tue, 14 Jul 2015 07:41:11 -0400 Received: from xavier.telenet-ops.be ([195.130.132.52]:45901 "EHLO xavier.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752161AbbGNLlK (ORCPT ); Tue, 14 Jul 2015 07:41:10 -0400 Received: from ayla.of.borg ([84.193.93.87]) by xavier.telenet-ops.be with bizsmtp id sBh71q00f1t5w8s01Bh77Q; Tue, 14 Jul 2015 13:41:08 +0200 Received: from ramsan.of.borg ([192.168.97.29] helo=ramsan) by ayla.of.borg with esmtp (Exim 4.82) (envelope-from ) id 1ZEyaB-0004IM-JH; Tue, 14 Jul 2015 13:41:07 +0200 Received: from geert by ramsan with local (Exim 4.82) (envelope-from ) id 1ZEyaC-0000id-BJ; Tue, 14 Jul 2015 13:41:08 +0200 From: Geert Uytterhoeven To: Daniel Lezcano , Thomas Gleixner Cc: linux-pm@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH v2] clocksource: sh_cmt: Only perform clocksource suspend/resume if enabled Date: Tue, 14 Jul 2015 13:41:04 +0200 Message-Id: <1436874064-2729-1-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 1.9.1 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Spam-Status: No, score=-8.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently the sh_cmt clocksource timer is disabled or enabled unconditionally on clocksource suspend resp. resume, even if a better clocksource is present (e.g. arch_sys_counter) and the sh_cmt clocksource is not enabled. As sh_cmt is a syscore device when its timer is enabled, this may lead to a genpd.prepared_count imbalance in the presence of PM Domains, which may cause a lock-up during reboot after s2ram. During suspend: - pm_genpd_prepare() is called for all non-syscore devices (incl. sh_cmt), increasing genpd.prepared_count for each device, - clocksource.suspend() is called for all clocksource devices, - sh_cmt_clocksource_suspend() calls sh_cmt_stop(), which is a no-op as the clocksource was not enabled. During resume: - clocksource.resume() is called for all clocksource devices, - sh_cmt_clocksource_resume() calls sh_cmt_start(), which enables the clocksource timer, and turns sh_cmt into a syscore device, - pm_genpd_complete() is called for all non-syscore devices (excl. sh_cmt now!), decreasing genpd.prepared_count for each device but sh_cmt. Now genpd.prepared_count of the PM Domain containing sh_cmt is still 1 instead of zero. On subsequent suspend/resume cycles, sh_cmt is still a syscore device, hence it's skipped for pm_genpd_{prepare,complete}(), keeping the imbalance of genpd.prepared_count at 1. During reboot: - platform_drv_shutdown() is called for any platform device that has a driver with a .shutdown() method (only rcar-dmac on R-Car Gen2), - platform_drv_shutdown() calls dev_pm_domain_detach(), which calls genpd_dev_pm_detach(), - genpd_dev_pm_detach() keeps calling pm_genpd_remove_device() until it doesn't return -EAGAIN[*], - If the device is part of the same PM Domain as sh_cmt, pm_genpd_remove_device() always fails with -EAGAIN due to genpd.prepared_count > 0. - Infinite loop in genpd_dev_pm_detach()[*]. [*] Commit 93af5e9354432828 ("PM / Domains: Avoid infinite loops in attach/detach code") already limited the number of loop iterations, avoiding the lock-up. To fix this, only disable or enable the clocksource timer on clocksource suspend resp. resume if the clocksource was enabled. This was tested on r8a7791/koelsch with the CPG Clock Domain: - using arch_sys_counter as the clocksource, which is the default, and which showed the problem, - using sh_cmt as a clocksource ("echo ffca0000.timer > \ /sys/devices/system/clocksource/clocksource0/current_clocksource"), which behaves the same as before. Signed-off-by: Geert Uytterhoeven Acked-by: Laurent Pinchart --- v1 was part of "[PATCH 0/2] PM / Domains: Infinite loop during reboot" (https://lkml.org/lkml/2015/6/18/212). The other part has been applied already (commit 93af5e9354432828). v2: - Add Acked-by, - Add a reference to the commit that fixed the infinite loop in the core PM Domain code. --- drivers/clocksource/sh_cmt.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c index d56d4e0e3fb3956d..ef799532a7a7963e 100644 --- a/drivers/clocksource/sh_cmt.c +++ b/drivers/clocksource/sh_cmt.c @@ -661,6 +661,9 @@ static void sh_cmt_clocksource_suspend(struct clocksource *cs) { struct sh_cmt_channel *ch = cs_to_sh_cmt(cs); + if (!ch->cs_enabled) + return; + sh_cmt_stop(ch, FLAG_CLOCKSOURCE); pm_genpd_syscore_poweroff(&ch->cmt->pdev->dev); } @@ -669,6 +672,9 @@ static void sh_cmt_clocksource_resume(struct clocksource *cs) { struct sh_cmt_channel *ch = cs_to_sh_cmt(cs); + if (!ch->cs_enabled) + return; + pm_genpd_syscore_poweron(&ch->cmt->pdev->dev); sh_cmt_start(ch, FLAG_CLOCKSOURCE); }