From patchwork Thu Dec 15 01:36:02 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lin Ming X-Patchwork-Id: 131510 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 6CAC91007D7 for ; Thu, 15 Dec 2011 12:36:33 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758540Ab1LOBgQ (ORCPT ); Wed, 14 Dec 2011 20:36:16 -0500 Received: from mga11.intel.com ([192.55.52.93]:23058 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758521Ab1LOBgO (ORCPT ); Wed, 14 Dec 2011 20:36:14 -0500 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga102.fm.intel.com with ESMTP; 14 Dec 2011 17:36:14 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="96327474" Received: from minggr.sh.intel.com ([10.239.36.47]) by fmsmga001.fm.intel.com with ESMTP; 14 Dec 2011 17:36:13 -0800 From: Lin Ming To: Jeff Garzik , James Bottomley , Alan Stern , Tejun Heo Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-pm@vger.kernel.org Subject: [PATCH v2 1/2] [SCSI]: runtime resume parent for child's system-resume Date: Thu, 15 Dec 2011 09:36:02 +0800 Message-Id: <1323912963-26146-2-git-send-email-ming.m.lin@intel.com> X-Mailer: git-send-email 1.7.2.5 In-Reply-To: <1323912963-26146-1-git-send-email-ming.m.lin@intel.com> References: <1323912963-26146-1-git-send-email-ming.m.lin@intel.com> Sender: linux-ide-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ide@vger.kernel.org [Patch description from Alan Stern] If a child device was runtime-suspended when a system suspend began, then there will be nothing to prevent its parent from runtime-suspending as soon as it is woken up during the system resume. Then when the time comes to resume the child, the resume will fail because the parent is already back at low power. On the other hand, there are some devices which should remain at low power across an entire suspend-resume cycle. The details depend on the device and the platform. This suggests that the PM core is not the right place to solve the problem. One possible solution is for the subsystem or device driver to call pm_runtime_get_sync(dev->parent) at the start of the system-resume procedure and pm_runtime_put_sync(dev->parent) at the end. Acked-by: Alan Stern Signed-off-by: Lin Ming --- drivers/scsi/scsi_pm.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/drivers/scsi/scsi_pm.c b/drivers/scsi/scsi_pm.c index a633076..bf8bf79 100644 --- a/drivers/scsi/scsi_pm.c +++ b/drivers/scsi/scsi_pm.c @@ -72,8 +72,17 @@ static int scsi_bus_resume_common(struct device *dev) { int err = 0; - if (scsi_is_sdev_device(dev)) + if (scsi_is_sdev_device(dev)) { + /* + * Parent device may have runtime suspended as soon as + * it is woken up during the system resume. + * + * Resume it on behalf of child. + */ + pm_runtime_get_sync(dev->parent); err = scsi_dev_type_resume(dev); + pm_runtime_put_sync(dev->parent); + } if (err == 0) { pm_runtime_disable(dev);