From 298e3d15d7576b03eb2915970e400c1c6e64c75f Mon Sep 17 00:00:00 2001
From: Nate Lawson <njl@FreeBSD.org>
Date: Thu, 5 Aug 2004 06:54:16 +0000
Subject: [PATCH] Work around non-compliant BIOS PCI link devices.  Some
 systems have the following behavior:

* Link devices return invalid status (_STA) values.  The results are very
  unreliable -- sometimes never present.  Just ignore the status and pick
  the best configuration from _PRS.

* Link devices return invalid current settings (_CRS).  Even after setting
  the link value, many systems still return a different setting for _CRS.
  When setting an IRQ, don't bother to check _CRS to see if we succeeded.
  Note that we still check _CRS before routing and this should be addressed
  as well.

Since this is a sensitive area, leave the old behavior accessible via
uncommenting the define for ACPI_OLD_PCI_LINK at the top of the file.  Once
this has been thoroughly tested, this option and the code it covers will
be removed.

Thanks to Len Brown at Intel for informing us of these issues as he worked
around them in Linux.
---
 sys/dev/acpica/acpi_pci_link.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/sys/dev/acpica/acpi_pci_link.c b/sys/dev/acpica/acpi_pci_link.c
index 400aa14de3a4..669aba41f279 100644
--- a/sys/dev/acpica/acpi_pci_link.c
+++ b/sys/dev/acpica/acpi_pci_link.c
@@ -24,6 +24,9 @@
  * SUCH DAMAGE.
  */
 
+/* XXX Uncomment this if you have new PCI IRQ problems starting 2004/8/5. */
+/* #define ACPI_OLD_PCI_LINK 1 */
+
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
@@ -73,10 +76,12 @@ static struct acpi_prt_entries acpi_prt_entries;
 
 static int	irq_penalty[MAX_ACPI_INTERRUPTS];
 
+#ifdef ACPI_OLD_PCI_LINK
 #define ACPI_STA_PRESENT	0x00000001
 #define ACPI_STA_ENABLE		0x00000002
 #define ACPI_STA_SHOWINUI	0x00000004
 #define ACPI_STA_FUNCTIONAL	0x00000008
+#endif /* ACPI_OLD_PCI_LINK */
 
 /*
  * PCI link object management
@@ -171,6 +176,7 @@ acpi_pci_link_entry_dump(struct acpi_prt_entry *entry)
 	    (int)entry->prt.Pin);
 }
 
+#ifdef ACPI_OLD_PCI_LINK
 static ACPI_STATUS
 acpi_pci_link_get_object_status(ACPI_HANDLE handle, UINT32 *sta)
 {
@@ -215,6 +221,7 @@ acpi_pci_link_get_object_status(ACPI_HANDLE handle, UINT32 *sta)
 	AcpiOsFree(buf.Pointer);
 	return_ACPI_STATUS (AE_OK);
 }
+#endif /* ACPI_OLD_PCI_LINK */
 
 static ACPI_STATUS
 acpi_pci_link_get_irq_resources(ACPI_RESOURCE *resources,
@@ -439,7 +446,9 @@ acpi_pci_link_add_prt(device_t pcidev, ACPI_PCI_ROUTING_TABLE *prt, int busno)
 {
 	ACPI_HANDLE		handle;
 	ACPI_STATUS		error;
+#ifdef ACPI_OLD_PCI_LINK
 	UINT32			sta;
+#endif
 	struct acpi_prt_entry	*entry;
 
 	ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
@@ -457,6 +466,11 @@ acpi_pci_link_add_prt(device_t pcidev, ACPI_PCI_ROUTING_TABLE *prt, int busno)
 		return_ACPI_STATUS (error);
 	}
 
+	/*
+	 * PCI link status (_STA) is unreliable.  Many systems return
+	 * erroneous values so we ignore it.
+	 */
+#ifdef ACPI_OLD_PCI_LINK
 	error = acpi_pci_link_get_object_status(handle, &sta);
 	if (ACPI_FAILURE(error)) {
 		ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
@@ -471,6 +485,7 @@ acpi_pci_link_add_prt(device_t pcidev, ACPI_PCI_ROUTING_TABLE *prt, int busno)
 		    acpi_name(handle)));
 		return_ACPI_STATUS (AE_ERROR);
 	}
+#endif /* ACPI_OLD_PCI_LINK */
 
 	TAILQ_FOREACH(entry, &acpi_prt_entries, links) {
 		if (entry->busno == busno &&
@@ -539,7 +554,9 @@ acpi_pci_link_set_irq(struct acpi_pci_link_entry *link, UINT8 irq)
 	ACPI_STATUS		error;
 	ACPI_RESOURCE		resbuf;
 	ACPI_BUFFER		crsbuf;
+#ifdef ACPI_OLD_PCI_LINK
 	UINT32			sta;
+#endif
 
 	ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 
@@ -614,7 +631,13 @@ acpi_pci_link_set_irq(struct acpi_pci_link_entry *link, UINT8 irq)
 
 	AcpiOsFree(crsbuf.Pointer);
 	link->current_irq = 0;
+	error = AE_OK;
 
+	/*
+	 * PCI link status (_STA) is unreliable.  Many systems return
+	 * erroneous values so we ignore it.
+	 */
+#ifdef ACPI_OLD_PCI_LINK
 	error = acpi_pci_link_get_object_status(link->handle, &sta);
 	if (ACPI_FAILURE(error)) {
 		ACPI_DEBUG_PRINT((ACPI_DB_WARN,
@@ -629,7 +652,14 @@ acpi_pci_link_set_irq(struct acpi_pci_link_entry *link, UINT8 irq)
 		    acpi_name(link->handle)));
 		return_ACPI_STATUS (AE_ERROR);
 	}
+#endif /* ACPI_OLD_PCI_LINK */
 
+	/*
+	 * Many systems always return invalid values for current settings
+	 * (_CRS).  Since we can't trust the value returned, we have to
+	 * assume we were successful.
+	 */
+#ifdef ACPI_OLD_PCI_LINK
 	error = acpi_pci_link_get_current_irq(link, &link->current_irq);
 	if (ACPI_FAILURE(error)) {
 		ACPI_DEBUG_PRINT((ACPI_DB_WARN,
@@ -647,6 +677,7 @@ acpi_pci_link_set_irq(struct acpi_pci_link_entry *link, UINT8 irq)
 		link->current_irq = 0;
 		error = AE_ERROR;
 	}
+#endif /* ACPI_OLD_PCI_LINK */
 
 	return_ACPI_STATUS (error);
 }