ahci: disable FPDMA auto-activate optimization on NVIDIA AHCI

commit 453d3131ec7aab82eaaa8401a50522a337092aa8 upstream.

Mike Cui reported that his system with an NVIDIA MCP79 (aka MCP7A)
chipset stopped working with 2.6.32. The problem appears to be that
2.6.32 now enables the FPDMA auto-activate optimization in the ahci
driver. The drive works fine with this enabled on an Intel AHCI so
this appears to be a chipset bug.  Since MCP79 is a fairly recent
NVIDIA chipset and we don't have any info on whether any other NVIDIA
chipsets have this issue, disable FPDMA AA optimization on all NVIDIA
AHCI controllers for now.

Should address http://bugzilla.kernel.org/show_bug.cgi?id=14922

Signed-off-by: Robert Hancock <hancockrwd@gmail.com>
While-we-investigate-issue-this-patch-looks-good-to-me-by:
	Prajakta Gudadhe <pgudadhe@nvidia.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 9b375028318a6806f220a8e35ff646adb038cae6..a587046e9966436f6824e4d996164f55a48225d9 100644 (file)
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -3074,8 +3074,16 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
        ahci_save_initial_config(pdev, hpriv);
 
        /* prepare host */
-       if (hpriv->cap & HOST_CAP_NCQ)
-               pi.flags |= ATA_FLAG_NCQ | ATA_FLAG_FPDMA_AA;
+       if (hpriv->cap & HOST_CAP_NCQ) {
+               pi.flags |= ATA_FLAG_NCQ;
+               /* Auto-activate optimization is supposed to be supported on
+                  all AHCI controllers indicating NCQ support, but it seems
+                  to be broken at least on some NVIDIA MCP79 chipsets.
+                  Until we get info on which NVIDIA chipsets don't have this
+                  issue, if any, disable AA on all NVIDIA AHCIs. */
+               if (pdev->vendor != PCI_VENDOR_ID_NVIDIA)
+                       pi.flags |= ATA_FLAG_FPDMA_AA;
+       }
 
        if (hpriv->cap & HOST_CAP_PMP)
                pi.flags |= ATA_FLAG_PMP;