PCI: Disable ASPM if BIOS asks us to

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> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

PCI: Disable ASPM if BIOS asks us to
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> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Matthew Garrett · Jesse Barnes
1 parent 8d80528696
Showing 3 changed files with 22 additions and 5 deletions Side-by-side Diff
drivers/pci/pci-acpi.c
drivers/pci/pcie/aspm.c
include/linux/pci-aspm.h
@@ -399,6 +399,7 @@
  
 	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();
 	}
  
@@ -68,7 +68,7 @@
 	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 @@
 {
 	/* 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 @@
 	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 @@
 	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 @@
 	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) &&
@@ -898,6 +905,12 @@
 }
  
 __setup("pcie_aspm=", pcie_aspm_disable);
+
+void pcie_clear_aspm(void)
+{
+	if (!aspm_force)
+		aspm_clear_state = 1;
+}
  
 void pcie_no_aspm(void)
 {
@@ -27,6 +27,7 @@
 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 pci_disable_link_state(struct pci_dev *pdev, int state)
 {
 }
-
+static inline void pcie_clear_aspm(void)
+{
+}
 static inline void pcie_no_aspm(void)
 {
 }
...	...	@@ -399,6 +399,7 @@
399	399
400	400	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
401	401	printk(KERN_INFO"ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
	402	+ pcie_clear_aspm();
402	403	pcie_no_aspm();
403	404	}
404	405
...	...	@@ -68,7 +68,7 @@
68	68	struct aspm_latency acceptable[8];
69	69	};
70	70
71		-static int aspm_disabled, aspm_force;
	71	+static int aspm_disabled, aspm_force, aspm_clear_state;
72	72	static DEFINE_MUTEX(aspm_lock);
73	73	static LIST_HEAD(link_list);
74	74
...	...	@@ -139,7 +139,7 @@
139	139	{
140	140	/* Don't enable Clock PM if the link is not Clock PM capable */
141	141	if (!link->clkpm_capable && enable)
142		- return;
	142	+ enable = 0;
143	143	/* Need nothing if the specified equals to current state */
144	144	if (link->clkpm_enabled == enable)
145	145	return;
...	...	@@ -498,6 +498,10 @@
498	498	struct pci_dev *child;
499	499	int pos;
500	500	u32 reg32;
	501	+
	502	+ if (aspm_clear_state)
	503	+ return -EINVAL;
	504	+
501	505	/*
502	506	* Some functions in a slot might not all be PCIe functions,
503	507	* very strange. Disable ASPM for the whole slot
504	508
...	...	@@ -563,12 +567,15 @@
563	567	struct pcie_link_state *link;
564	568	int blacklist = !!pcie_aspm_sanity_check(pdev);
565	569
566		- if (aspm_disabled \|\| !pci_is_pcie(pdev) \|\| pdev->link_state)
	570	+ if (!pci_is_pcie(pdev) \|\| pdev->link_state)
567	571	return;
568	572	if (pdev->pcie_type != PCI_EXP_TYPE_ROOT_PORT &&
569	573	pdev->pcie_type != PCI_EXP_TYPE_DOWNSTREAM)
570	574	return;
571	575
	576	+ if (aspm_disabled && !aspm_clear_state)
	577	+ return;
	578	+
572	579	/* VIA has a strange chipset, root port is under a bridge */
573	580	if (pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT &&
574	581	pdev->bus->self)
...	...	@@ -641,7 +648,7 @@
641	648	struct pci_dev *parent = pdev->bus->self;
642	649	struct pcie_link_state link, root, *parent_link;
643	650
644		- if (aspm_disabled \|\| !pci_is_pcie(pdev) \|\|
	651	+ if ((aspm_disabled && !aspm_clear_state) \|\| !pci_is_pcie(pdev) \|\|
645	652	!parent \|\| !parent->link_state)
646	653	return;
647	654	if ((parent->pcie_type != PCI_EXP_TYPE_ROOT_PORT) &&
...	...	@@ -898,6 +905,12 @@
898	905	}
899	906
900	907	__setup("pcie_aspm=", pcie_aspm_disable);
	908	+
	909	+void pcie_clear_aspm(void)
	910	+{
	911	+ if (!aspm_force)
	912	+ aspm_clear_state = 1;
	913	+}
901	914
902	915	void pcie_no_aspm(void)
903	916	{
...	...	@@ -27,6 +27,7 @@
27	27	extern void pcie_aspm_exit_link_state(struct pci_dev *pdev);
28	28	extern void pcie_aspm_pm_state_change(struct pci_dev *pdev);
29	29	extern void pci_disable_link_state(struct pci_dev *pdev, int state);
	30	+extern void pcie_clear_aspm(void);
30	31	extern void pcie_no_aspm(void);
31	32	#else
32	33	static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
...	...	@@ -41,7 +42,9 @@
41	42	static inline void pci_disable_link_state(struct pci_dev *pdev, int state)
42	43	{
43	44	}
44		-
	45	+static inline void pcie_clear_aspm(void)
	46	+{
	47	+}
45	48	static inline void pcie_no_aspm(void)
46	49	{
47	50	}