PCI: Disable ASPM if BIOS asks us to

1 files changed, 144 insertions, 0 deletions

diff --git a/pci-disable-aspm-if-bios-asks-us-to.patch b/pci-disable-aspm-if-bios-asks-us-to.patch
new file mode 100644
index 000000000..f9f2935fd
--- /dev/null
+++ b/pci-disable-aspm-if-bios-asks-us-to.patch
@@ -0,0 +1,144 @@
+From linux-kernel-owner@vger.kernel.org Mon Dec  6 14:01:17 2010
+From:	Matthew Garrett <mjg@redhat.com>
+To:	linux-pci@vger.kernel.org
+Cc:	linux-kernel@vger.kernel.org, jbarnes@virtuousgeek.org,
+	Matthew Garrett <mjg@redhat.com>
+Subject: [PATCH v2] PCI: Disable ASPM if BIOS asks us to
+Date:	Mon,  6 Dec 2010 14:00:56 -0500
+Message-Id: <1291662056-6055-1-git-send-email-mjg@redhat.com>
+
+We currently refuse to touch the ASPM registers if the BIOS tells us that
+ASPM isn't supported. This can cause problems if the BIOS has (for any
+reason) enabled ASPM on some devices anyway. Change the code such that we
+explicitly clear ASPM if the FADT indicates that ASPM isn't supported,
+and make sure we tidy up appropriately on device removal in order to deal
+with the hotplug case. If ASPM is disabled because the BIOS doesn't hand
+over control then we won't touch the registers.
+
+Signed-off-by: Matthew Garrett <mjg@redhat.com>
+---
+
+Implement Rafael's suggestion to use two separate functions, and also
+ensure that we clear the clkpm bit as well as the ASPM bits.
+
+ drivers/pci/pci-acpi.c   |    1 +
+ drivers/pci/pcie/aspm.c  |   21 +++++++++++++++++----
+ include/linux/pci-aspm.h |    5 ++++-
+ 3 files changed, 22 insertions(+), 5 deletions(-)
+
+diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
+index 24e19c5..d7ea699 100644
+--- a/drivers/pci/pci-acpi.c
++++ b/drivers/pci/pci-acpi.c
+@@ -399,6 +399,7 @@ 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 7122281..8112415 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;
++static int aspm_disabled, aspm_force, aspm_clear_state;
+ static DEFINE_MUTEX(aspm_lock);
+ static LIST_HEAD(link_list);
+ 
+@@ -139,7 +139,7 @@ static void pcie_set_clkpm(struct pcie_link_state *link, int enable)
+ {
+ 	/* Don't enable Clock PM if the link is not Clock PM capable */
+ 	if (!link->clkpm_capable && enable)
+-		return;
++		enable = 0;
+ 	/* Need nothing if the specified equals to current state */
+ 	if (link->clkpm_enabled == enable)
+ 		return;
+@@ -498,6 +498,10 @@ static int pcie_aspm_sanity_check(struct pci_dev *pdev)
+ 	struct pci_dev *child;
+ 	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
+@@ -563,12 +567,15 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev)
+ 	struct pcie_link_state *link;
+ 	int blacklist = !!pcie_aspm_sanity_check(pdev);
+ 
+-	if (aspm_disabled || !pci_is_pcie(pdev) || pdev->link_state)
++	if (!pci_is_pcie(pdev) || pdev->link_state)
+ 		return;
+ 	if (pdev->pcie_type != PCI_EXP_TYPE_ROOT_PORT &&
+ 	    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)
+@@ -641,7 +648,7 @@ 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 || !pci_is_pcie(pdev) ||
++	if ((aspm_disabled && !aspm_clear_state) || !pci_is_pcie(pdev) ||
+ 	    !parent || !parent->link_state)
+ 		return;
+ 	if ((parent->pcie_type != PCI_EXP_TYPE_ROOT_PORT) &&
+@@ -899,6 +906,12 @@ static int __init pcie_aspm_disable(char *str)
+ 
+ __setup("pcie_aspm=", pcie_aspm_disable);
+ 
++void pci_clear_aspm(void)
++{
++	if (!aspm_force)
++		aspm_clear_state = 1;
++}
++
+ void pcie_no_aspm(void)
+ {
+ 	if (!aspm_force)
+diff --git a/include/linux/pci-aspm.h b/include/linux/pci-aspm.h
+index 91ba0b3..ce68105 100644
+--- a/include/linux/pci-aspm.h
++++ b/include/linux/pci-aspm.h
+@@ -27,6 +27,7 @@ extern void pcie_aspm_init_link_state(struct pci_dev *pdev);
+ extern void pcie_aspm_exit_link_state(struct pci_dev *pdev);
+ extern void pcie_aspm_pm_state_change(struct pci_dev *pdev);
+ extern void pci_disable_link_state(struct pci_dev *pdev, int state);
++extern void pcie_clear_aspm(void);
+ extern void pcie_no_aspm(void);
+ #else
+ static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
+@@ -41,7 +42,9 @@ static inline void pcie_aspm_pm_state_change(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_no_aspm(void)
+ {
+ }
+-- 
+1.7.3.2
+
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