2 files changed, 41 insertions, 8 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 4e4c295a049f..1f9a7a03847b 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -47,6 +47,19 @@ unsigned long pci_cardbus_mem_size = DEFAULT_CARDBUS_MEM_SIZE;
 unsigned long pci_hotplug_io_size  = DEFAULT_HOTPLUG_IO_SIZE;
 unsigned long pci_hotplug_mem_size = DEFAULT_HOTPLUG_MEM_SIZE;
 
+#ifndef PCI_CACHE_LINE_BYTES
+#define PCI_CACHE_LINE_BYTES L1_CACHE_BYTES
+#endif
+
+/*
+ * The default CLS is used if arch didn't set CLS explicitly and not
+ * all pci devices agree on the same value.  Arch can override either
+ * the dfl or actual value as it sees fit.  Don't forget this is
+ * measured in 32-bit words, not bytes.
+ */
+u8 pci_dfl_cache_line_size __initdata = PCI_CACHE_LINE_BYTES >> 2;
+u8 pci_cache_line_size;
+
 /**
  * pci_bus_max_busnr - returns maximum PCI bus number of given bus' children
  * @bus: pointer to PCI bus structure to search
@@ -1883,14 +1896,6 @@ void pci_clear_mwi(struct pci_dev *dev)
 
 #else
 
-#ifndef PCI_CACHE_LINE_BYTES
-#define PCI_CACHE_LINE_BYTES L1_CACHE_BYTES
-#endif
-
-/* This can be overridden by arch code. */
-/* Don't forget this is measured in 32-bit words, not bytes */
-u8 pci_cache_line_size = PCI_CACHE_LINE_BYTES / 4;
-
 /**
  * pci_set_cacheline_size - ensure the CACHE_LINE_SIZE register is programmed
  * @dev: the PCI device for which MWI is to be enabled
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 245d2cdb4765..1812ae7698de 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -2595,9 +2595,37 @@ void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev)
 static int __init pci_apply_final_quirks(void)
 {
         struct pci_dev *dev = NULL;
+        u8 cls = 0;
+        u8 tmp;
+
+        if (pci_cache_line_size)
+                printk(KERN_DEBUG "PCI: CLS %u bytes\n",
+                       pci_cache_line_size << 2);
 
         while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
                 pci_fixup_device(pci_fixup_final, dev);
+                /*
+                 * If arch hasn't set it explicitly yet, use the CLS
+                 * value shared by all PCI devices.  If there's a
+                 * mismatch, fall back to the default value.
+                 */
+                if (!pci_cache_line_size) {
+                        pci_read_config_byte(dev, PCI_CACHE_LINE_SIZE, &tmp);
+                        if (!cls)
+                                cls = tmp;
+                        if (!tmp || cls == tmp)
+                                continue;
+
+                        printk(KERN_DEBUG "PCI: CLS mismatch (%u != %u), "
+                               "using %u bytes\n", cls << 2, tmp << 2,
+                               pci_dfl_cache_line_size << 2);
+                        pci_cache_line_size = pci_dfl_cache_line_size;
+                }
+        }
+        if (!pci_cache_line_size) {
+                printk(KERN_DEBUG "PCI: CLS %u bytes, default %u\n",
+                       cls << 2, pci_dfl_cache_line_size << 2);
+                pci_cache_line_size = cls;
         }
 
         return 0;