2 files changed, 51 insertions, 2 deletions

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 2141a31f176b..15a23031833f 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -431,8 +431,7 @@ static const struct ata_port_info ahci_port_info[] = {
         [board_ahci_sb600] =
         {
                 AHCI_HFLAGS     (AHCI_HFLAG_IGN_SERR_INTERNAL |
-                                 AHCI_HFLAG_32BIT_ONLY | AHCI_HFLAG_NO_MSI |
-                                 AHCI_HFLAG_SECT255),
+                                 AHCI_HFLAG_NO_MSI | AHCI_HFLAG_SECT255),
                 .flags          = AHCI_FLAG_COMMON,
                 .pio_mask       = ATA_PIO4,
                 .udma_mask      = ATA_UDMA6,
@@ -2585,6 +2584,51 @@ static void ahci_p5wdh_workaround(struct ata_host *host)
         }
 }
 
+/*
+ * SB600 ahci controller on ASUS M2A-VM can't do 64bit DMA with older
+ * BIOS.  The oldest version known to be broken is 0901 and working is
+ * 1501 which was released on 2007-10-26.  Force 32bit DMA on anything
+ * older than 1501.  Please read bko#9412 for more info.
+ */
+static bool ahci_asus_m2a_vm_32bit_only(struct pci_dev *pdev)
+{
+        static const struct dmi_system_id sysids[] = {
+                {
+                        .ident = "ASUS M2A-VM",
+                        .matches = {
+                                DMI_MATCH(DMI_BOARD_VENDOR,
+                                          "ASUSTeK Computer INC."),
+                                DMI_MATCH(DMI_BOARD_NAME, "M2A-VM"),
+                        },
+                },
+                { }
+        };
+        const char *cutoff_mmdd = "10/26";
+        const char *date;
+        int year;
+
+        if (pdev->bus->number != 0 || pdev->devfn != PCI_DEVFN(0x12, 0) ||
+            !dmi_check_system(sysids))
+                return false;
+
+        /*
+         * Argh.... both version and date are free form strings.
+         * Let's hope they're using the same date format across
+         * different versions.
+         */
+        date = dmi_get_system_info(DMI_BIOS_DATE);
+        year = dmi_get_year(DMI_BIOS_DATE);
+        if (date && strlen(date) >= 10 && date[2] == '/' && date[5] == '/' &&
+            (year > 2007 ||
+             (year == 2007 && strncmp(date, cutoff_mmdd, 5) >= 0)))
+                return false;
+
+        dev_printk(KERN_WARNING, &pdev->dev, "ASUS M2A-VM: BIOS too old, "
+                   "forcing 32bit DMA, update BIOS\n");
+
+        return true;
+}
+
 static bool ahci_broken_system_poweroff(struct pci_dev *pdev)
 {
         static const struct dmi_system_id broken_systems[] = {
@@ -2745,6 +2789,10 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
         if (board_id == board_ahci_sb700 && pdev->revision >= 0x40)
                 hpriv->flags &= ~AHCI_HFLAG_IGN_SERR_INTERNAL;
 
+        /* apply ASUS M2A_VM quirk */
+        if (ahci_asus_m2a_vm_32bit_only(pdev))
+                hpriv->flags |= AHCI_HFLAG_32BIT_ONLY;
+
         if (!(hpriv->flags & AHCI_HFLAG_NO_MSI))
                 pci_enable_msi(pdev);
 
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 5f1b5400d96a..24c84ae81527 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -596,6 +596,7 @@ int dmi_get_year(int field)
 
         return year;
 }
+EXPORT_SYMBOL(dmi_get_year);
 
 /**
  *      dmi_walk - Walk the DMI table and get called back for every record