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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 CC2B4C5DF60 for ; Thu, 7 Nov 2019 20:09:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A177B2166E for ; Thu, 7 Nov 2019 20:09:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lixom-net.20150623.gappssmtp.com header.i=@lixom-net.20150623.gappssmtp.com header.b="OSQ58w+Q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725785AbfKGUJQ (ORCPT ); Thu, 7 Nov 2019 15:09:16 -0500 Received: from mail-il1-f196.google.com ([209.85.166.196]:37232 "EHLO mail-il1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726231AbfKGUJQ (ORCPT ); Thu, 7 Nov 2019 15:09:16 -0500 Received: by mail-il1-f196.google.com with SMTP id s5so3000256iln.4 for ; Thu, 07 Nov 2019 12:09:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lixom-net.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=n78FTesTpTJ/BSxJVBGWGsxOBEQaJP9PhxbGA4r4iXs=; b=OSQ58w+QwGhCdyzBMBRwZRUHTZ5uUdY5Q8wpDqk6wTm1BN4AQWkVJP+mxLn3O1xKJI NHAEhD7OvvuyZUBT0VX6OStvYV1wPuH+98zXPOOj6CFJNRd7DknMBmpAodzC/FMhH/n9 z5upvFKxrVdCr2JIoRQP9M0uASWSHNnWg/NZ8hoVPKfTq7r4fCyG3kcTVwOKxAjvbYt6 4Zk/CNOux3lwuVziuy03ALQ1815alAq3ogiw/H5giUsjr2XExcm/wxp5nY3saZVGUzsV a9CKR3ZC08yjDL2ah1TBoZxRSnBPAHDbF30bqzmaH1hXJbhHBCqzFK2oraXr7MM4akKq w/uA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=n78FTesTpTJ/BSxJVBGWGsxOBEQaJP9PhxbGA4r4iXs=; b=nO9/qV5253wWUFjGIACr5KECiJxGXEvyoQ5mBiqkHml6CpJNvxcTkrWr9V5zc9Q3Qx Tsq2GfL7qQMCY9kabooKu7epj/KK3wRhuMFM8oNLapBDWyj2cykcFWNCExigcMO+kI+Y S14qR9Ou4VfQ/0kzKjP3lEXTR63t4bM/jSKbnN70+wDVdJWQYKiIKiSyIRTLCa/HyNho 1n1gmibkOZDcjAgMZAd9wrW2C8it+kKIHP5W0/7Jx8YYqHffCeyqxngyfqsoN6eDYsur dohWHBI1AsR+dZgOs11G7+uq+c6jTFP+ZQAgJbnKz3qFjY8NFvfqMFmDw662hSwVmm1a jwcA== X-Gm-Message-State: APjAAAWK42XupuE9j9urMBpib/zp8yWGz6Y9CUEBaNhJ35S8vC/aaXw/ 2hfwpb1ZZ6dF/QhKlY/ftMeNAUCrNl56jntQKbT0Qg== X-Google-Smtp-Source: APXvYqxluSqAu+N734VP6mdWZsNX+hE3qJdUV4umr4wntSPeGfNfSxx5fhGbskmP6UPxh7BN7/R4EnznrMWxse8n0D8= X-Received: by 2002:a92:1b1c:: with SMTP id b28mr6612291ilb.278.1573157353544; Thu, 07 Nov 2019 12:09:13 -0800 (PST) MIME-Version: 1.0 References: <20191025202004.GA147688@google.com> <1ade6a9f-9532-c400-9bb0-4e68ed5752ce@linux.intel.com> In-Reply-To: <1ade6a9f-9532-c400-9bb0-4e68ed5752ce@linux.intel.com> From: Olof Johansson Date: Thu, 7 Nov 2019 12:09:02 -0800 Message-ID: Subject: Re: [PATCH] PCI/DPC: Add pcie_ports=dpc-native parameter to bring back old behavior To: sathyanarayanan.kuppuswamy@linux.intel.com Cc: Bjorn Helgaas , Keith Busch , linux-pci@vger.kernel.org, Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Nov 7, 2019 at 12:02 PM Kuppuswamy Sathyanarayanan wrote: > > Hi, > > On 10/25/19 1:20 PM, Bjorn Helgaas wrote: > > On Wed, Oct 23, 2019 at 12:22:05PM -0700, Olof Johansson wrote: > >> In commit eed85ff4c0da7 ("PCI/DPC: Enable DPC only if AER is available"), > >> the behavior was changed such that native (kernel) handling of DPC > >> got tied to whether the kernel also handled AER. While this is what > >> the standard recommends, there are BIOSes out there that lack the DPC > >> handling since it was never required in the past. > > Some systems do not grant OS control of AER via _OSC. I guess the > > problem is that on those systems, the OS DPC driver used to work, but > > after eed85ff4c0da7, it does not. Right? > > I need some clarification on this issue. Do you mean in these systems, > firmware expects OS to handle DPC and AER, but it does not let OS know > about it via _OSC ? The OS and BIOS both assumed behavior as before eed85ff4c0da7 -- AER handled by firmware but DPC handled by kernel. I.e. a classic case of "Sure, the spec says this, but in reality implementations relied on actual behavior", and someone had a regression and need a way to restore previous behavior. -Olof