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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 3037DC433E6 for ; Wed, 17 Mar 2021 19:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CE34A64F21 for ; Wed, 17 Mar 2021 19:23:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233216AbhCQTWr (ORCPT ); Wed, 17 Mar 2021 15:22:47 -0400 Received: from mga17.intel.com ([192.55.52.151]:10028 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231378AbhCQTWn (ORCPT ); Wed, 17 Mar 2021 15:22:43 -0400 IronPort-SDR: VX/jcGp75E7UGqhLpMxtDCCZ+LWzNUztuw99DtLpDsl+SuyuQDNSc3QRDaW/NvRDYZlI/i9zQc wj6GUFq4wfQA== X-IronPort-AV: E=McAfee;i="6000,8403,9926"; a="169448226" X-IronPort-AV: E=Sophos;i="5.81,257,1610438400"; d="scan'208";a="169448226" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2021 12:22:43 -0700 IronPort-SDR: IZ+KWvuirzQOoBPlEhvgFMnYGuqEEOR3NbsFumGkCBLPfsdSHxzHhLMWe4HLm+s/jKIJ4vzUWf hHYyKhlYmpYg== X-IronPort-AV: E=Sophos;i="5.81,257,1610438400"; d="scan'208";a="439507943" Received: from otc-nc-03.jf.intel.com (HELO otc-nc-03) ([10.54.39.36]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2021 12:22:42 -0700 Date: Wed, 17 Mar 2021 12:22:41 -0700 From: "Raj, Ashok" To: Lukas Wunner Cc: Dan Williams , Sathyanarayanan Kuppuswamy Natarajan , Kuppuswamy Sathyanarayanan , Bjorn Helgaas , Linux PCI , Linux Kernel Mailing List , Keith Busch , knsathya@kernel.org, Sinan Kaya , Ashok Raj Subject: Re: [PATCH v2 1/1] PCI: pciehp: Skip DLLSC handling if DPC is triggered Message-ID: <20210317192241.GE52280@otc-nc-03> References: <59cb30f5e5ac6d65427ceaadf1012b2ba8dbf66c.1615606143.git.sathyanarayanan.kuppuswamy@linux.intel.com> <20210317041342.GA19198@wunner.de> <20210317053114.GA32370@wunner.de> <20210317190952.GB27146@wunner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210317190952.GB27146@wunner.de> User-Agent: Mutt/1.5.24 (2015-08-30) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 17, 2021 at 08:09:52PM +0100, Lukas Wunner wrote: > On Wed, Mar 17, 2021 at 10:45:21AM -0700, Dan Williams wrote: > > Ah, ok, we're missing a flush of the hotplug event handler after the > > link is up to make sure the hotplug handler does not see the Link Up. > > I'm not immediately seeing how the new proposal ensures that there is > > no Link Up event still in flight after DPC completes its work. > > Wouldn't it be required to throw away Link Up to Link Up transitions? > > If you look at the new code added to pciehp_ist() by my patch... > > atomic_and(~PCI_EXP_SLTSTA_DLLSC, &ctrl->pending_events); > if (pciehp_check_link_active(ctrl) > 0) > events &= ~PCI_EXP_SLTSTA_DLLSC; When you have a Surprise Link Down and without any DPC, the link trains back up. Aren't we expected to take the slot down and add it as if a remove and add happens? without this change if slot-status == ON_STATE, DLLSC means we would power the slot off. Then we check link_active and bring the slot back on isn't it?