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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 282CFC18E5A for ; Wed, 11 Mar 2020 10:28:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F4113222C3 for ; Wed, 11 Mar 2020 10:28:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729003AbgCKK2Q (ORCPT ); Wed, 11 Mar 2020 06:28:16 -0400 Received: from mga06.intel.com ([134.134.136.31]:1938 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726000AbgCKK2P (ORCPT ); Wed, 11 Mar 2020 06:28:15 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Mar 2020 03:28:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,540,1574150400"; d="scan'208";a="353855467" Received: from lahna.fi.intel.com (HELO lahna) ([10.237.72.163]) by fmsmga001.fm.intel.com with SMTP; 11 Mar 2020 03:28:12 -0700 Received: by lahna (sSMTP sendmail emulation); Wed, 11 Mar 2020 12:28:11 +0200 Date: Wed, 11 Mar 2020 12:28:11 +0200 From: Mika Westerberg To: Kai-Heng Feng Cc: bhelgaas@google.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] PCI/PM: Skip link training delay for S3 resume Message-ID: <20200311102811.GA2540@lahna.fi.intel.com> References: <20200311045249.5200-1-kai.heng.feng@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200311045249.5200-1-kai.heng.feng@canonical.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Wed, Mar 11, 2020 at 12:52:49PM +0800, Kai-Heng Feng wrote: > Commit ad9001f2f411 ("PCI/PM: Add missing link delays required by the > PCIe spec") added a 1100ms delay on resume for bridges that don't > support Link Active Reporting. > > The commit also states that the delay can be skipped for S3, as the > firmware should already handled the case for us. Delay can be skipped if the firmware provides _DSM with function 8 implemented according to PCI firmwre spec 3.2 sec 4.6.8. > So let's skip the link training delay for S3, to save 1100ms resume > time. > > Signed-off-by: Kai-Heng Feng > --- > drivers/pci/pci-driver.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > index 0454ca0e4e3f..3050375bad04 100644 > --- a/drivers/pci/pci-driver.c > +++ b/drivers/pci/pci-driver.c > @@ -916,7 +916,8 @@ static int pci_pm_resume_noirq(struct device *dev) > pci_fixup_device(pci_fixup_resume_early, pci_dev); > pcie_pme_root_status_cleanup(pci_dev); > > - if (!skip_bus_pm && prev_state == PCI_D3cold) > + if (!skip_bus_pm && prev_state == PCI_D3cold > + && !pm_resume_via_firmware()) So this would need to check for the _DSM result as well. We do evaluate it in pci_acpi_optimize_delay() (drivers/pci/pci-acpi.c) and that ends up lowering ->d3cold_delay so maybe check that here. > pci_bridge_wait_for_secondary_bus(pci_dev); > > if (pci_has_legacy_pm_support(pci_dev)) > -- > 2.17.1