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,NICE_REPLY_A,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 F35A3C63777 for ; Fri, 20 Nov 2020 19:33:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C53C522264 for ; Fri, 20 Nov 2020 19:33:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727170AbgKTTdq (ORCPT ); Fri, 20 Nov 2020 14:33:46 -0500 Received: from mga02.intel.com ([134.134.136.20]:12079 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727123AbgKTTdp (ORCPT ); Fri, 20 Nov 2020 14:33:45 -0500 IronPort-SDR: udjQMAVt19rO1Tq9lNLsghmmZSwm7uUnUzwleajjCaLOEYXuP2tMb6AUUVLjvMB6ldsp/SDR7r bAh2H9uDxhnQ== X-IronPort-AV: E=McAfee;i="6000,8403,9811"; a="158570705" X-IronPort-AV: E=Sophos;i="5.78,357,1599548400"; d="scan'208";a="158570705" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Nov 2020 11:33:41 -0800 IronPort-SDR: WoO+Obmn5/ED39/fgvTEcyrPaElg84xz/tFCYOXkZd+sVDw8mAQdHmUnOtJ6tNMTTtBVZCuGcw Jm3eQ69RBFUA== X-IronPort-AV: E=Sophos;i="5.78,357,1599548400"; d="scan'208";a="545559814" Received: from jalynchx-mobl.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.254.69.108]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Nov 2020 11:33:41 -0800 Subject: Re: [PATCH 1/1] pci: pciehp: Handle MRL interrupts to enable slot for hotplug. To: "Raj, Ashok" , Lukas Wunner Cc: linux-pci@vger.kernel.org, Bjorn Helgaas , linux-kernel@vger.kernel.org References: <20200925230138.29011-1-ashok.raj@intel.com> <20201119075120.GA542@wunner.de> <20201119220807.GB102444@otc-nc-03> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <6fc4bb9e-d46b-062e-1731-69a165e6fb35@linux.intel.com> Date: Fri, 20 Nov 2020 11:33:37 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201119220807.GB102444@otc-nc-03> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi, On 11/19/20 2:08 PM, Raj, Ashok wrote: >> If an Attention Button is present, the current behavior is to bring up >> the hotplug slot as soon as presence or link is detected. We don't wait >> for a button press. This is intended as a convience feature to bring up >> slots as quickly as possible, but the behavior can be changed if the >> button press and 5 second delay is preferred. > No personal preference, I thought that is how the code in Linux was > earlier. > > Looks like we still don't subscribe to PDC if ATTN is present? So you don't > get an event until someone presses the button to process hotplug right? > > pciehp_hpc.c:pcie_enable_notification() > { > .... > > * Always enable link events: thus link-up and link-down shall > * always be treated as hotplug and unplug respectively. Enable > * presence detect only if Attention Button is not present. > */ > cmd = PCI_EXP_SLTCTL_DLLSCE; > if (ATTN_BUTTN(ctrl)) > cmd |= PCI_EXP_SLTCTL_ABPE; > else > cmd |= PCI_EXP_SLTCTL_PDCE; > .... > } > > > Looks like we still wait for button press to process. When you don't have a > power control yes the DLLSC would kick in and we would process them. but if > you have power control, you won't turn on until the button press? > Yes, as per current logic, if attention button is present, then we don't subscribe to PDC event changes. we wait for button press  to turn on/off the slot. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer