[PATCH] i386/x86-64 Fall back to type 1 access when no entry found

When there is no entry for a bus in MCFG fall back to type1.  This is
especially important on K8 systems where always some devices can't be accessed
using mmconfig (in particular the builtin northbridge doesn't support it for
its own devices)

Cc: <gregkh@suse.de>
Cc: <jgarzik@pobox.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 8 deletions

diff --git a/arch/i386/pci/mmconfig.c b/arch/i386/pci/mmconfig.c
index dfbf80c..cc787a7 100644
--- a/arch/i386/pci/mmconfig.c
+++ b/arch/i386/pci/mmconfig.c
@@ -30,10 +30,8 @@ static u32 get_base_addr(unsigned int seg, int bus)
 	while (1) {
 		++cfg_num;
 		if (cfg_num >= pci_mmcfg_config_num) {
-			/* something bad is going on, no cfg table is found. */
-			/* so we fall back to the old way we used to do this */
-			/* and just rely on the first entry to be correct. */
-			return pci_mmcfg_config[0].base_address;
+			/* Not found - fallback to type 1 */
+			return 0;
 		}
 		cfg = &pci_mmcfg_config[cfg_num];
 		if (cfg->pci_segment_group_number != seg)
@@ -44,9 +42,9 @@ static u32 get_base_addr(unsigned int seg, int bus)
 	}
 }
 
-static inline void pci_exp_set_dev_base(unsigned int seg, int bus, int devfn)
+static inline void pci_exp_set_dev_base(unsigned int base, int bus, int devfn)
 {
-	u32 dev_base = get_base_addr(seg, bus) | (bus << 20) | (devfn << 12);
+	u32 dev_base = base | (bus << 20) | (devfn << 12);
 	if (dev_base != mmcfg_last_accessed_device) {
 		mmcfg_last_accessed_device = dev_base;
 		set_fixmap_nocache(FIX_PCIE_MCFG, dev_base);
@@ -57,13 +55,18 @@ static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
 			  unsigned int devfn, int reg, int len, u32 *value)
 {
 	unsigned long flags;
+	u32 base;
 
 	if (!value || (bus > 255) || (devfn > 255) || (reg > 4095))
 		return -EINVAL;
 
+	base = get_base_addr(seg, bus);
+	if (!base)
+		return pci_conf1_read(seg,bus,devfn,reg,len,value);
+
 	spin_lock_irqsave(&pci_config_lock, flags);
 
-	pci_exp_set_dev_base(seg, bus, devfn);
+	pci_exp_set_dev_base(base, bus, devfn);
 
 	switch (len) {
 	case 1:
@@ -86,13 +89,18 @@ static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
 			   unsigned int devfn, int reg, int len, u32 value)
 {
 	unsigned long flags;
+	u32 base;
 
 	if ((bus > 255) || (devfn > 255) || (reg > 4095)) 
 		return -EINVAL;
 
+	base = get_base_addr(seg, bus);
+	if (!base)
+		return pci_conf1_write(seg,bus,devfn,reg,len,value);
+
 	spin_lock_irqsave(&pci_config_lock, flags);
 
-	pci_exp_set_dev_base(seg, bus, devfn);
+	pci_exp_set_dev_base(base, bus, devfn);
 
 	switch (len) {
 	case 1: