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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 F16FAC433FF for ; Mon, 5 Aug 2019 12:39:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C90B22067D for ; Mon, 5 Aug 2019 12:39:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726834AbfHEMjY (ORCPT ); Mon, 5 Aug 2019 08:39:24 -0400 Received: from mga01.intel.com ([192.55.52.88]:21458 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726508AbfHEMjY (ORCPT ); Mon, 5 Aug 2019 08:39:24 -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 fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Aug 2019 05:39:23 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,349,1559545200"; d="scan'208";a="192411599" Received: from lahna.fi.intel.com (HELO lahna) ([10.237.72.157]) by fmsmga001.fm.intel.com with SMTP; 05 Aug 2019 05:39:20 -0700 Received: by lahna (sSMTP sendmail emulation); Mon, 05 Aug 2019 15:39:20 +0300 Date: Mon, 5 Aug 2019 15:39:20 +0300 From: Mika Westerberg To: Greg Kroah-Hartman Cc: Justin Forbes , LKML , stable@vger.kernel.org, "Rafael J. Wysocki" , Sasha Levin Subject: Re: [PATCH 5.2 123/413] PCI: Add missing link delays required by the PCIe spec Message-ID: <20190805123920.GN2640@lahna.fi.intel.com> References: <20190724191735.096702571@linuxfoundation.org> <20190724191743.977277445@linuxfoundation.org> <20190803065000.GE10855@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190803065000.GE10855@kroah.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.11.4 (2019-03-13) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org Hi, On Sat, Aug 03, 2019 at 08:50:00AM +0200, Greg Kroah-Hartman wrote: > On Fri, Aug 02, 2019 at 12:06:39PM -0500, Justin Forbes wrote: > > On Wed, Jul 24, 2019 at 3:31 PM Greg Kroah-Hartman > > wrote: > > > > > > [ Upstream commit c2bf1fc212f7e6f25ace1af8f0b3ac061ea48ba5 ] > > > > > > Currently Linux does not follow PCIe spec regarding the required delays > > > after reset. A concrete example is a Thunderbolt add-in-card that > > > consists of a PCIe switch and two PCIe endpoints: > > > > > > +-1b.0-[01-6b]----00.0-[02-6b]--+-00.0-[03]----00.0 TBT controller > > > +-01.0-[04-36]-- DS hotplug port > > > +-02.0-[37]----00.0 xHCI controller > > > \-04.0-[38-6b]-- DS hotplug port > > > > > > The root port (1b.0) and the PCIe switch downstream ports are all PCIe > > > gen3 so they support 8GT/s link speeds. > > > > > > We wait for the PCIe hierarchy to enter D3cold (runtime): > > > > > > pcieport 0000:00:1b.0: power state changed by ACPI to D3cold > > > > > > When it wakes up from D3cold, according to the PCIe 4.0 section 5.8 the > > > PCIe switch is put to reset and its power is re-applied. This means that > > > we must follow the rules in PCIe 4.0 section 6.6.1. > > > > > > For the PCIe gen3 ports we are dealing with here, the following applies: > > > > > > With a Downstream Port that supports Link speeds greater than 5.0 > > > GT/s, software must wait a minimum of 100 ms after Link training > > > completes before sending a Configuration Request to the device > > > immediately below that Port. Software can determine when Link training > > > completes by polling the Data Link Layer Link Active bit or by setting > > > up an associated interrupt (see Section 6.7.3.3). > > > > > > Translating this into the above topology we would need to do this (DLLLA > > > stands for Data Link Layer Link Active): > > > > > > pcieport 0000:00:1b.0: wait for 100ms after DLLLA is set before access to 0000:01:00.0 > > > pcieport 0000:02:00.0: wait for 100ms after DLLLA is set before access to 0000:03:00.0 > > > pcieport 0000:02:02.0: wait for 100ms after DLLLA is set before access to 0000:37:00.0 > > > > > > I've instrumented the kernel with additional logging so we can see the > > > actual delays the kernel performs: > > > > > > pcieport 0000:00:1b.0: power state changed by ACPI to D0 > > > pcieport 0000:00:1b.0: waiting for D3cold delay of 100 ms > > > pcieport 0000:00:1b.0: waking up bus > > > pcieport 0000:00:1b.0: waiting for D3hot delay of 10 ms > > > pcieport 0000:00:1b.0: restoring config space at offset 0x2c (was 0x60, writing 0x60) > > > ... > > > pcieport 0000:00:1b.0: PME# disabled > > > pcieport 0000:01:00.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > ... > > > pcieport 0000:01:00.0: PME# disabled > > > pcieport 0000:02:00.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > ... > > > pcieport 0000:02:00.0: PME# disabled > > > pcieport 0000:02:01.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > ... > > > pcieport 0000:02:01.0: restoring config space at offset 0x4 (was 0x100000, writing 0x100407) > > > pcieport 0000:02:01.0: PME# disabled > > > pcieport 0000:02:02.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > ... > > > pcieport 0000:02:02.0: PME# disabled > > > pcieport 0000:02:04.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > ... > > > pcieport 0000:02:04.0: PME# disabled > > > pcieport 0000:02:01.0: PME# enabled > > > pcieport 0000:02:01.0: waiting for D3hot delay of 10 ms > > > pcieport 0000:02:04.0: PME# enabled > > > pcieport 0000:02:04.0: waiting for D3hot delay of 10 ms > > > thunderbolt 0000:03:00.0: restoring config space at offset 0x14 (was 0x0, writing 0x8a040000) > > > ... > > > thunderbolt 0000:03:00.0: PME# disabled > > > xhci_hcd 0000:37:00.0: restoring config space at offset 0x10 (was 0x0, writing 0x73f00000) > > > ... > > > xhci_hcd 0000:37:00.0: PME# disabled > > > > > > For the switch upstream port (01:00.0) we wait for 100ms but not taking > > > into account the DLLLA requirement. We then wait 10ms for D3hot -> D0 > > > transition of the root port and the two downstream hotplug ports. This > > > means that we deviate from what the spec requires. > > > > > > Performing the same check for system sleep (s2idle) transitions we can > > > see following when resuming from s2idle: > > > > > > pcieport 0000:00:1b.0: power state changed by ACPI to D0 > > > pcieport 0000:00:1b.0: restoring config space at offset 0x2c (was 0x60, writing 0x60) > > > ... > > > pcieport 0000:01:00.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > ... > > > pcieport 0000:02:02.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > pcieport 0000:02:02.0: restoring config space at offset 0x2c (was 0x0, writing 0x0) > > > pcieport 0000:02:01.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > pcieport 0000:02:04.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > pcieport 0000:02:02.0: restoring config space at offset 0x28 (was 0x0, writing 0x0) > > > pcieport 0000:02:00.0: restoring config space at offset 0x3c (was 0x1ff, writing 0x201ff) > > > pcieport 0000:02:02.0: restoring config space at offset 0x24 (was 0x10001, writing 0x1fff1) > > > pcieport 0000:02:01.0: restoring config space at offset 0x2c (was 0x0, writing 0x60) > > > pcieport 0000:02:02.0: restoring config space at offset 0x20 (was 0x0, writing 0x73f073f0) > > > pcieport 0000:02:04.0: restoring config space at offset 0x2c (was 0x0, writing 0x60) > > > pcieport 0000:02:01.0: restoring config space at offset 0x28 (was 0x0, writing 0x60) > > > pcieport 0000:02:00.0: restoring config space at offset 0x2c (was 0x0, writing 0x0) > > > pcieport 0000:02:02.0: restoring config space at offset 0x1c (was 0x101, writing 0x1f1) > > > pcieport 0000:02:04.0: restoring config space at offset 0x28 (was 0x0, writing 0x60) > > > pcieport 0000:02:01.0: restoring config space at offset 0x24 (was 0x10001, writing 0x1ff10001) > > > pcieport 0000:02:00.0: restoring config space at offset 0x28 (was 0x0, writing 0x0) > > > pcieport 0000:02:02.0: restoring config space at offset 0x18 (was 0x0, writing 0x373702) > > > pcieport 0000:02:04.0: restoring config space at offset 0x24 (was 0x10001, writing 0x49f12001) > > > pcieport 0000:02:01.0: restoring config space at offset 0x20 (was 0x0, writing 0x73e05c00) > > > pcieport 0000:02:00.0: restoring config space at offset 0x24 (was 0x10001, writing 0x1fff1) > > > pcieport 0000:02:04.0: restoring config space at offset 0x20 (was 0x0, writing 0x89f07400) > > > pcieport 0000:02:01.0: restoring config space at offset 0x1c (was 0x101, writing 0x5151) > > > pcieport 0000:02:00.0: restoring config space at offset 0x20 (was 0x0, writing 0x8a008a00) > > > pcieport 0000:02:02.0: restoring config space at offset 0xc (was 0x10000, writing 0x10020) > > > pcieport 0000:02:04.0: restoring config space at offset 0x1c (was 0x101, writing 0x6161) > > > pcieport 0000:02:01.0: restoring config space at offset 0x18 (was 0x0, writing 0x360402) > > > pcieport 0000:02:00.0: restoring config space at offset 0x1c (was 0x101, writing 0x1f1) > > > pcieport 0000:02:04.0: restoring config space at offset 0x18 (was 0x0, writing 0x6b3802) > > > pcieport 0000:02:02.0: restoring config space at offset 0x4 (was 0x100000, writing 0x100407) > > > pcieport 0000:02:00.0: restoring config space at offset 0x18 (was 0x0, writing 0x30302) > > > pcieport 0000:02:01.0: restoring config space at offset 0xc (was 0x10000, writing 0x10020) > > > pcieport 0000:02:04.0: restoring config space at offset 0xc (was 0x10000, writing 0x10020) > > > pcieport 0000:02:00.0: restoring config space at offset 0xc (was 0x10000, writing 0x10020) > > > pcieport 0000:02:01.0: restoring config space at offset 0x4 (was 0x100000, writing 0x100407) > > > pcieport 0000:02:04.0: restoring config space at offset 0x4 (was 0x100000, writing 0x100407) > > > pcieport 0000:02:00.0: restoring config space at offset 0x4 (was 0x100000, writing 0x100407) > > > xhci_hcd 0000:37:00.0: restoring config space at offset 0x10 (was 0x0, writing 0x73f00000) > > > ... > > > thunderbolt 0000:03:00.0: restoring config space at offset 0x14 (was 0x0, writing 0x8a040000) > > > > > > This is even worse. None of the mandatory delays are performed. If this > > > would be S3 instead of s2idle then according to PCI FW spec 3.2 section > > > 4.6.8. there is a specific _DSM that allows the OS to skip the delays > > > but this platform does not provide the _DSM and does not go to S3 anyway > > > so no firmware is involved that could already handle these delays. > > > > > > In this particular Intel Coffee Lake platform these delays are not > > > actually needed because there is an additional delay as part of the ACPI > > > power resource that is used to turn on power to the hierarchy but since > > > that additional delay is not required by any of standards (PCIe, ACPI) > > > it is not present in the Intel Ice Lake, for example where missing the > > > mandatory delays causes pciehp to start tearing down the stack too early > > > (links are not yet trained). > > > > > > For this reason, change the PCIe portdrv PM resume hooks so that they > > > perform the mandatory delays before the downstream component gets > > > resumed. We perform the delays before port services are resumed because > > > otherwise pciehp might find that the link is not up (even if it is just > > > training) and tears-down the hierarchy. > > > > > > > We have gotten multiple reports in Fedora that this patch has broken > > suspend for users of 5.1.20 and 5.2 stable kernels. > > And is the issue also in 5.3-rcX kernels? If so, can we either get this > reverted there, or find the fix for it? AFAIK the issue is also in v5.3-rcX. I started looking at the issue now. Hopefully there is a better solution than revert but let's see.