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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D819CC3DA7D for ; Tue, 3 Jan 2023 19:51:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238379AbjACTu7 (ORCPT ); Tue, 3 Jan 2023 14:50:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238993AbjACTut (ORCPT ); Tue, 3 Jan 2023 14:50:49 -0500 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72AD9DEF9 for ; Tue, 3 Jan 2023 11:50:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1672775443; x=1704311443; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=KxhYgpbgG8q84CFYisj7x9zwz/CLDzDNZTCOaAYPpCs=; b=dRuckrKM6T8qz52JEj8r4qQnMn2fX5scKK4o5bAAD748bHIc/M7TkaZ9 FvOfb9vQwd8Mgv1c4nKtQwEaFZt3SHOP9NgZ8/lkCjIjU8mOVhD9Cq/EI pikgIsjEwpi4VRqNtLMBFroJbcJjrTkZvdGHjKxe7zN2W2RAmHoUeshT7 ay05fSK5tW/vkPY2OvGpOzN2BL9I2CUI22eokle4GDtyJUl7TSifzDXsL zJ5CXAEvB/wtrf4JnmSD9vFx9t2uBlLwWEWwWgLCSjnGeWREzCOn/Mm64 PcmLCRbR/228FGwwOXvWNV6IBLvqagfFt6gACEHjr4xZqO/eNGRtsChN1 Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10579"; a="348964056" X-IronPort-AV: E=Sophos;i="5.96,297,1665471600"; d="scan'208";a="348964056" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jan 2023 11:50:42 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10579"; a="654908863" X-IronPort-AV: E=Sophos;i="5.96,297,1665471600"; d="scan'208";a="654908863" Received: from jjha-mobl1.amr.corp.intel.com (HELO [10.209.61.244]) ([10.209.61.244]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Jan 2023 11:50:42 -0800 Message-ID: <86ea6848-7608-f42d-c918-9dba618502b1@linux.intel.com> Date: Tue, 3 Jan 2023 11:50:42 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.4.2 Subject: Re: [PATCH 1/3] PCI/PM: Observe reset delay irrespective of bridge_d3 Content-Language: en-US To: Lukas Wunner , Bjorn Helgaas , linux-pci@vger.kernel.org Cc: Keith Busch , Ashok Raj , Ravi Kishore Koppuravuri , Mika Westerberg , Sheng Bi , Stanislav Spassov , Yang Su References: From: Sathyanarayanan Kuppuswamy In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 12/31/22 10:33 AM, Lukas Wunner wrote: > If a PCI bridge is suspended to D3cold upon entering system sleep, > resuming it entails a Fundamental Reset per PCIe r6.0 sec 5.8. > > The delay prescribed after a Fundamental Reset in PCIe r6.0 sec 6.6.1 > is sought to be observed by: > > pci_pm_resume_noirq() > pci_pm_bridge_power_up_actions() > pci_bridge_wait_for_secondary_bus() > > However, pci_bridge_wait_for_secondary_bus() bails out if the bridge_d3 > flag is not set. That flag indicates whether a bridge is allowed to > suspend to D3cold at *runtime*. > > Hence *no* delay is observed on resume from system sleep if runtime > D3cold is forbidden. That doesn't make any sense, so drop the bridge_d3 > check from pci_bridge_wait_for_secondary_bus(). > > The purpose of the bridge_d3 check was probably to avoid delays if a > bridge remained in D0 during suspend. However the sole caller of > pci_bridge_wait_for_secondary_bus(), pci_pm_bridge_power_up_actions(), > is only invoked if the previous power state was D3cold. Hence the > additional bridge_d3 check seems superfluous. > > Fixes: ad9001f2f411 ("PCI/PM: Add missing link delays required by the PCIe spec") > Tested-by: Ravi Kishore Koppuravuri > Signed-off-by: Lukas Wunner > Cc: stable@vger.kernel.org # v5.5+ > Cc: Mika Westerberg > --- Reviewed-by: Kuppuswamy Sathyanarayanan > drivers/pci/pci.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index fba95486caaf..f43f3e84f634 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -4964,7 +4964,7 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev) > if (pci_dev_is_disconnected(dev)) > return; > > - if (!pci_is_bridge(dev) || !dev->bridge_d3) > + if (!pci_is_bridge(dev)) > return; > > down_read(&pci_bus_sem); -- Sathyanarayanan Kuppuswamy Linux Kernel Developer