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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 422A6C433DF for ; Sat, 10 Oct 2020 02:36:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4409206D4 for ; Sat, 10 Oct 2020 02:36:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729822AbgJJCgO (ORCPT ); Fri, 9 Oct 2020 22:36:14 -0400 Received: from mga09.intel.com ([134.134.136.24]:57783 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730056AbgJJC00 (ORCPT ); Fri, 9 Oct 2020 22:26:26 -0400 IronPort-SDR: 2TIsLqBOiSpvm+GgIrm1gWbPP4W3gYt/dbJ0+fBW2MbKgKvJOd9Ck8wPKDhXefKG9Co63qJ6Kq gnRGQhNOiCFg== X-IronPort-AV: E=McAfee;i="6000,8403,9769"; a="165669753" X-IronPort-AV: E=Sophos;i="5.77,357,1596524400"; d="scan'208";a="165669753" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Oct 2020 19:26:08 -0700 IronPort-SDR: fuUo3wUtHngd8LxHqK9efmt7IPF1UVCqO2Ekyo8/R++wQVLjAivVUPb8wloj0p6XIJkhH0RZO4 x+X+6Z/v6QTg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,357,1596524400"; d="scan'208";a="350031268" Received: from lkp-server02.sh.intel.com (HELO inn.sh.intel.com) ([10.239.97.151]) by fmsmga002.fm.intel.com with ESMTP; 09 Oct 2020 19:26:07 -0700 From: Zhang Rui To: linux-acpi@vger.kernel.org, rjw@rjwysocki.net Cc: sukumar.ghorai@intel.com, rui.zhang@intel.com Subject: [PATCH] acpi: reboot: fix racing after writing to ACPI RESET_REG Date: Sat, 10 Oct 2020 10:26:06 +0800 Message-Id: <20201010022606.27669-1-rui.zhang@intel.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org According to the ACPI spec, "The system must reset immediately following the write to the ACPI RESET_REG register.", but there are cases that the system does not follow this and results in racing with the subsequetial reboot mechanism, which brings unexpected behavior. Fix this by adding a 15ms delay after writing to the ACPI RESET_REG. Reported-by: Ghorai, Sukumar Signed-off-by: Zhang Rui --- drivers/acpi/reboot.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c index ca707f5b521d..88e6b083d702 100644 --- a/drivers/acpi/reboot.c +++ b/drivers/acpi/reboot.c @@ -3,6 +3,7 @@ #include #include #include +#include #ifdef CONFIG_PCI static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value) @@ -66,4 +67,10 @@ void acpi_reboot(void) acpi_reset(); break; } + + /* + * delay for 15ms in case the system does not shutdown immediately after + * writing to the ACPI reset register + */ + mdelay(15); } -- 2.17.1