Add patch to rework ASPM handling from Matthew Garrett

1 files changed, 287 insertions, 0 deletions

diff --git a/pci-Rework-ASPM-disable-code.patch b/pci-Rework-ASPM-disable-code.patch
new file mode 100644
index 000000000..d6fb24320
--- /dev/null
+++ b/pci-Rework-ASPM-disable-code.patch
@@ -0,0 +1,287 @@
+Path: news.gmane.org!not-for-mail
+From: Matthew Garrett <mjg@redhat.com>
+Newsgroups: gmane.linux.acpi.devel,gmane.linux.kernel.pci,gmane.linux.kernel
+Subject: [PATCH] pci: Rework ASPM disable code
+Date: Thu, 10 Nov 2011 16:38:33 -0500
+Lines: 232
+Approved: news@gmane.org
+Message-ID: <1320961113-5050-1-git-send-email-mjg@redhat.com>
+NNTP-Posting-Host: lo.gmane.org
+X-Trace: dough.gmane.org 1320961145 13112 80.91.229.12 (10 Nov 2011 21:39:05 GMT)
+X-Complaints-To: usenet@dough.gmane.org
+NNTP-Posting-Date: Thu, 10 Nov 2011 21:39:05 +0000 (UTC)
+Cc: linux-pci@vger.kernel.org, linux-acpi@vger.kernel.org,
+	linux-kernel@vger.kernel.org, Matthew Garrett <mjg@redhat.com>
+To: jbarnes@virtuousgeek.org
+Original-X-From: linux-acpi-owner@vger.kernel.org Thu Nov 10 22:38:57 2011
+Return-path: <linux-acpi-owner@vger.kernel.org>
+Envelope-to: glad-acpi-devel@lo.gmane.org
+Original-Received: from vger.kernel.org ([209.132.180.67])
+	by lo.gmane.org with esmtp (Exim 4.69)
+	(envelope-from <linux-acpi-owner@vger.kernel.org>)
+	id 1ROcKm-0003jN-CL
+	for glad-acpi-devel@lo.gmane.org; Thu, 10 Nov 2011 22:38:56 +0100
+Original-Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
+	id S1751342Ab1KJViu (ORCPT <rfc822;glad-acpi-devel@m.gmane.org>);
+	Thu, 10 Nov 2011 16:38:50 -0500
+Original-Received: from mx1.redhat.com ([209.132.183.28]:32030 "EHLO mx1.redhat.com"
+	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
+	id S1750805Ab1KJVit (ORCPT <rfc822;linux-acpi@vger.kernel.org>);
+	Thu, 10 Nov 2011 16:38:49 -0500
+Original-Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22])
+	by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id pAALcmdw013333
+	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK);
+	Thu, 10 Nov 2011 16:38:49 -0500
+Original-Received: from cavan.codon.org.uk (ovpn-113-157.phx2.redhat.com [10.3.113.157])
+	by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id pAALclkW022022
+	(version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=NO);
+	Thu, 10 Nov 2011 16:38:48 -0500
+Original-Received: from 209-6-41-104.c3-0.smr-ubr1.sbo-smr.ma.cable.rcn.com ([209.6.41.104] helo=localhost.localdomain)
+	by cavan.codon.org.uk with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)
+	(Exim 4.72)
+	(envelope-from <mjg@redhat.com>)
+	id 1ROcKa-0000F4-E4; Thu, 10 Nov 2011 21:38:44 +0000
+X-SA-Do-Not-Run: Yes
+X-SA-Exim-Connect-IP: 209.6.41.104
+X-SA-Exim-Mail-From: mjg@redhat.com
+X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false
+X-Scanned-By: MIMEDefang 2.68 on 10.5.11.22
+Original-Sender: linux-acpi-owner@vger.kernel.org
+Precedence: bulk
+List-ID: <linux-acpi.vger.kernel.org>
+X-Mailing-List: linux-acpi@vger.kernel.org
+Xref: news.gmane.org gmane.linux.acpi.devel:51182 gmane.linux.kernel.pci:12503 gmane.linux.kernel:1214427
+Archived-At: <http://permalink.gmane.org/gmane.linux.acpi.devel/51182>
+
+Right now we forcibly clear ASPM state on all devices if the BIOS indicates
+that the feature isn't supported. Based on the Microsoft presentation
+"PCI Express In Depth for Windows Vista and Beyond", I'm starting to think
+that this may be an error. The implication is that unless the platform
+grants full control via _OSC, Windows will not touch any PCIe features -
+including ASPM. In that case clearing ASPM state would be an error unless
+the platform has granted us that control.
+
+This patch reworks the ASPM disabling code such that the actual clearing
+of state is triggered by a successful handoff of PCIe control to the OS.
+The general ASPM code undergoes some changes in order to ensure that the
+ability to clear the bits isn't overridden by ASPM having already been
+disabled. Further, this theoretically now allows for situations where
+only a subset of PCIe roots hand over control, leaving the others in the
+BIOS state.
+
+It's difficult to know for sure that this is the right thing to do -
+there's zero public documentation on the interaction between all of these
+components. But enough vendors enable ASPM on platforms and then set this
+bit that it seems likely that they're expecting the OS to leave them alone.
+
+Measured to save around 5W on an idle Thinkpad X220.
+
+Signed-off-by: Matthew Garrett <mjg@redhat.com>
+---
+ drivers/acpi/pci_root.c  |    7 +++++
+ drivers/pci/pci-acpi.c   |    1 -
+ drivers/pci/pcie/aspm.c  |   58 +++++++++++++++++++++++++++++----------------
+ include/linux/pci-aspm.h |    4 +-
+ 4 files changed, 46 insertions(+), 24 deletions(-)
+
+diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
+index 2672c79..7aff631 100644
+--- a/drivers/acpi/pci_root.c
++++ b/drivers/acpi/pci_root.c
+@@ -596,6 +596,13 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
+ 		if (ACPI_SUCCESS(status)) {
+ 			dev_info(root->bus->bridge,
+ 				"ACPI _OSC control (0x%02x) granted\n", flags);
++			if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
++				/*
++				 * We have ASPM control, but the FADT indicates
++				 * that it's unsupported. Clear it.
++				 */
++				pcie_clear_aspm(root->bus);
++			}
+ 		} else {
+ 			dev_info(root->bus->bridge,
+ 				"ACPI _OSC request failed (%s), "
+diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
+index 4ecb640..c8e7585 100644
+--- a/drivers/pci/pci-acpi.c
++++ b/drivers/pci/pci-acpi.c
+@@ -395,7 +395,6 @@ static int __init acpi_pci_init(void)
+ 
+ 	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
+ 		printk(KERN_INFO"ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
+-		pcie_clear_aspm();
+ 		pcie_no_aspm();
+ 	}
+ 
+diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
+index cbfbab1..1cfbf22 100644
+--- a/drivers/pci/pcie/aspm.c
++++ b/drivers/pci/pcie/aspm.c
+@@ -68,7 +68,7 @@ struct pcie_link_state {
+ 	struct aspm_latency acceptable[8];
+ };
+ 
+-static int aspm_disabled, aspm_force, aspm_clear_state;
++static int aspm_disabled, aspm_force;
+ static bool aspm_support_enabled = true;
+ static DEFINE_MUTEX(aspm_lock);
+ static LIST_HEAD(link_list);
+@@ -500,9 +500,6 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
+ 	int pos;
+ 	u32 reg32;
+ 
+-	if (aspm_clear_state)
+-		return -EINVAL;
+-
+ 	/*
+ 	 * Some functions in a slot might not all be PCIe functions,
+ 	 * very strange. Disable ASPM for the whole slot
+@@ -574,9 +571,6 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
+ 	    pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)
+ 		return;
+ 
+-	if (aspm_disabled && !aspm_clear_state)
+-		return;
+-
+ 	/* VIA has a strange chipset, root port is under a bridge */
+ 	if (pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT &&
+ 	    pdev->bus->self)
+@@ -608,7 +602,7 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
+ 	 * the BIOS's expectation, we'll do so once pci_enable_device() is
+ 	 * called.
+ 	 */
+-	if (aspm_policy != POLICY_POWERSAVE || aspm_clear_state) {
++	if (aspm_policy != POLICY_POWERSAVE) {
+ 		pcie_config_aspm_path(link);
+ 		pcie_set_clkpm(link, policy_to_clkpm_state(link));
+ 	}
+@@ -649,8 +643,7 @@ void pcie_aspm_exit_link_state(struct pci_dev *pdev)
+ 	struct pci_dev *parent = pdev->bus->self;
+ 	struct pcie_link_state *link, *root, *parent_link;
+ 
+-	if ((aspm_disabled && !aspm_clear_state) || !pci_is_pcie(pdev) ||
+-	    !parent || !parent->link_state)
++	if (!pci_is_pcie(pdev) || !parent || !parent->link_state)
+ 		return;
+ 	if ((parent->pcie_type != PCI_EXP_TYPE_ROOT_PORT) &&
+ 	    (parent->pcie_type != PCI_EXP_TYPE_DOWNSTREAM))
+@@ -734,13 +727,18 @@ void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
+  * pci_disable_link_state - disable pci device's link state, so the link will
+  * never enter specific states
+  */
+-static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
++static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem,
++				     bool force)
+ {
+ 	struct pci_dev *parent = pdev->bus->self;
+ 	struct pcie_link_state *link;
+ 
+-	if (aspm_disabled || !pci_is_pcie(pdev))
++	if (aspm_disabled && !force)
++		return;
++
++	if (!pci_is_pcie(pdev))
+ 		return;
++
+ 	if (pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT ||
+ 	    pdev->pcie_type == PCI_EXP_TYPE_DOWNSTREAM)
+ 		parent = pdev;
+@@ -768,16 +766,31 @@ static void __pci_disable_link_state(struct pci_dev *pdev, int state, bool sem)
+ 
+ void pci_disable_link_state_locked(struct pci_dev *pdev, int state)
+ {
+-	__pci_disable_link_state(pdev, state, false);
++	__pci_disable_link_state(pdev, state, false, false);
+ }
+ EXPORT_SYMBOL(pci_disable_link_state_locked);
+ 
+ void pci_disable_link_state(struct pci_dev *pdev, int state)
+ {
+-	__pci_disable_link_state(pdev, state, true);
++	__pci_disable_link_state(pdev, state, true, false);
+ }
+ EXPORT_SYMBOL(pci_disable_link_state);
+ 
++void pcie_clear_aspm(struct pci_bus *bus)
++{
++	struct pci_dev *child;
++
++	/*
++	 * Clear any ASPM setup that the firmware has carried out on this bus
++	 */
++	list_for_each_entry(child, &bus->devices, bus_list) {
++		__pci_disable_link_state(child, PCIE_LINK_STATE_L0S |
++					 PCIE_LINK_STATE_L1 |
++					 PCIE_LINK_STATE_CLKPM,
++					 false, true);
++	}
++}
++
+ static int pcie_aspm_set_policy(const char *val, struct kernel_param *kp)
+ {
+ 	int i;
+@@ -935,6 +948,7 @@ void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev)
+ static int __init pcie_aspm_disable(char *str)
+ {
+ 	if (!strcmp(str, "off")) {
++		aspm_policy = POLICY_DEFAULT;
+ 		aspm_disabled = 1;
+ 		aspm_support_enabled = false;
+ 		printk(KERN_INFO "PCIe ASPM is disabled\n");
+@@ -947,16 +961,18 @@ static int __init pcie_aspm_disable(char *str)
+ 
+ __setup("pcie_aspm=", pcie_aspm_disable);
+ 
+-void pcie_clear_aspm(void)
+-{
+-	if (!aspm_force)
+-		aspm_clear_state = 1;
+-}
+-
+ void pcie_no_aspm(void)
+ {
+-	if (!aspm_force)
++	/*
++	 * Disabling ASPM is intended to prevent the kernel from modifying
++	 * existing hardware state, not to clear existing state. To that end:
++	 * (a) set policy to POLICY_DEFAULT in order to avoid changing state
++	 * (b) prevent userspace from changing policy
++	 */
++	if (!aspm_force) {
++		aspm_policy = POLICY_DEFAULT;
+ 		aspm_disabled = 1;
++	}
+ }
+ 
+ /**
+diff --git a/include/linux/pci-aspm.h b/include/linux/pci-aspm.h
+index 7cea7b6..c832014 100644
+--- a/include/linux/pci-aspm.h
++++ b/include/linux/pci-aspm.h
+@@ -29,7 +29,7 @@ extern void pcie_aspm_pm_state_change(struct pci_dev *pdev);
+ extern void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
+ extern void pci_disable_link_state(struct pci_dev *pdev, int state);
+ extern void pci_disable_link_state_locked(struct pci_dev *pdev, int state);
+-extern void pcie_clear_aspm(void);
++extern void pcie_clear_aspm(struct pci_bus *bus);
+ extern void pcie_no_aspm(void);
+ #else
+ static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
+@@ -47,7 +47,7 @@ static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
+ static inline void pci_disable_link_state(struct pci_dev *pdev, int state)
+ {
+ }
+-static inline void pcie_clear_aspm(void)
++static inline void pcie_clear_aspm(struct pci_bus *bus)
+ {
+ }
+ static inline void pcie_no_aspm(void)
+-- 
+1.7.7.1
+
+--
+To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
+the body of a message to majordomo@vger.kernel.org
+More majordomo info at  http://vger.kernel.org/majordomo-info.html
+