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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 66660C433ED for ; Wed, 28 Apr 2021 17:21:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1759F6143B for ; Wed, 28 Apr 2021 17:21:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241549AbhD1RWD (ORCPT ); Wed, 28 Apr 2021 13:22:03 -0400 Received: from mga14.intel.com ([192.55.52.115]:31875 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229931AbhD1RWD (ORCPT ); Wed, 28 Apr 2021 13:22:03 -0400 IronPort-SDR: XWMHNS+wPjLie1H7hBz2NfTsDEJbeLaQDEl6YlivxlsW5VAmlKjLVIZty42WlftZQ1UmtT+gAe fdAkZRfcBULg== X-IronPort-AV: E=McAfee;i="6200,9189,9968"; a="196358545" X-IronPort-AV: E=Sophos;i="5.82,258,1613462400"; d="scan'208";a="196358545" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2021 10:21:17 -0700 IronPort-SDR: cEvlCi3kOBH3dTkRN8SBpGaWOVoi90VfEqm9CSV9CtLns7T37tsTWnyFaetDwLqTl6FVw2AxIQ M7f0fLuWrMfQ== X-IronPort-AV: E=Sophos;i="5.82,258,1613462400"; d="scan'208";a="425680637" Received: from turnerrx-desk.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.254.37.37]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2021 10:21:14 -0700 Subject: Re: [RFC PATCH] PCI/APCI: Move acpi_pci_osc_support() check to negotiation phase To: Joerg Roedel , Bjorn Helgaas , rjw@rjwysocki.net, Len Brown Cc: linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Joerg Roedel References: <20210428081857.10322-1-joro@8bytes.org> From: "Kuppuswamy, Sathyanarayanan" Message-ID: Date: Wed, 28 Apr 2021 10:21:12 -0700 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: <20210428081857.10322-1-joro@8bytes.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 4/28/21 1:18 AM, Joerg Roedel wrote: > From: Joerg Roedel > > The acpi_pci_osc_support() does an _OSC query with _OSC supported set > to what the OS supports but a zero _OSC control value. This is > problematic on some platforms where the firmware allows to configure > whether DPC is under OS or Firmware control. Do we run acpi_pci_osc_support() only to check whether _OSC is supported ? Or does it serve any other purpose. > > When DPC is configured to be under OS control these platforms will > issue a warning in the firmware log that the OS does not support DPC. Also, is there any other benefit from this patch other than fixing a warning message in firmware? > > Avoid an _OSC query with _OSC control set to zero by moving the > supported check into the acpi_pci_osc_control_set() path. This is > still early enough to fail as nothing before that depends on the > results of acpi_pci_osc_support(). > > As a result the acpi_pci_osc_support() function can be removed and > acpi_pci_query_osc() be simplified because it no longer called with a > NULL pointer for *control. > > Signed-off-by: Joerg Roedel > --- > drivers/acpi/pci_root.c | 50 ++++++++++++++++------------------------- > 1 file changed, 19 insertions(+), 31 deletions(-) > > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c > index dcd593766a64..530ecf4970b1 100644 > --- a/drivers/acpi/pci_root.c > +++ b/drivers/acpi/pci_root.c > @@ -199,16 +199,11 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root, > > support &= OSC_PCI_SUPPORT_MASKS; > support |= root->osc_support_set; > + *control &= OSC_PCI_CONTROL_MASKS; > > capbuf[OSC_QUERY_DWORD] = OSC_QUERY_ENABLE; > capbuf[OSC_SUPPORT_DWORD] = support; > - if (control) { > - *control &= OSC_PCI_CONTROL_MASKS; > - capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set; > - } else { > - /* Run _OSC query only with existing controls. */ > - capbuf[OSC_CONTROL_DWORD] = root->osc_control_set; > - } > + capbuf[OSC_CONTROL_DWORD] = *control | root->osc_control_set; > > status = acpi_pci_run_osc(root->device->handle, capbuf, &result); > if (ACPI_SUCCESS(status)) { > @@ -219,11 +214,6 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root, > return status; > } > > -static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags) > -{ > - return acpi_pci_query_osc(root, flags, NULL); > -} > - > struct acpi_pci_root *acpi_pci_find_root(acpi_handle handle) > { > struct acpi_pci_root *root; > @@ -346,7 +336,8 @@ EXPORT_SYMBOL_GPL(acpi_get_pci_dev); > * _OSC bits the BIOS has granted control of, but its contents are meaningless > * on failure. > **/ > -static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 req) > +static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 > + *mask, u32 req, u32 support) > { > struct acpi_pci_root *root; > acpi_status status; > @@ -370,7 +361,7 @@ static acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 *mask, u32 r > > /* Need to check the available controls bits before requesting them. */ > while (*mask) { > - status = acpi_pci_query_osc(root, root->osc_support_set, mask); > + status = acpi_pci_query_osc(root, support, mask); > if (ACPI_FAILURE(status)) > return status; > if (ctrl == *mask) > @@ -433,18 +424,6 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm, > support |= OSC_PCI_EDR_SUPPORT; > > decode_osc_support(root, "OS supports", support); > - status = acpi_pci_osc_support(root, support); > - if (ACPI_FAILURE(status)) { > - *no_aspm = 1; > - > - /* _OSC is optional for PCI host bridges */ > - if ((status == AE_NOT_FOUND) && !is_pcie) > - return; > - > - dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n", > - acpi_format_exception(status)); > - return; > - } > > if (pcie_ports_disabled) { > dev_info(&device->dev, "PCIe port services disabled; not requesting _OSC control\n"); > @@ -483,7 +462,8 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm, > > requested = control; > status = acpi_pci_osc_control_set(handle, &control, > - OSC_PCI_EXPRESS_CAPABILITY_CONTROL); > + OSC_PCI_EXPRESS_CAPABILITY_CONTROL, > + support); > if (ACPI_SUCCESS(status)) { > decode_osc_control(root, "OS now controls", control); > if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) { > @@ -496,10 +476,8 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm, > *no_aspm = 1; > } > } else { > - decode_osc_control(root, "OS requested", requested); > - decode_osc_control(root, "platform willing to grant", control); > - dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n", > - acpi_format_exception(status)); > + /* Platform wants to control PCIe features */ > + root->osc_support_set = 0; > > /* > * We want to disable ASPM here, but aspm_disabled > @@ -509,6 +487,16 @@ static void negotiate_os_control(struct acpi_pci_root *root, int *no_aspm, > * root scan. > */ > *no_aspm = 1; > + > + /* _OSC is optional for PCI host bridges */ > + if ((status == AE_NOT_FOUND) && !is_pcie) > + return; > + > + decode_osc_control(root, "OS requested", requested); > + decode_osc_control(root, "platform willing to grant", control); > + dev_info(&device->dev, "_OSC: platform retains control of PCIe features (%s)\n", > + acpi_format_exception(status)); > + > } > } > > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer