sata_vsc: use default cache line size if non-zero
This modifies drivers/ata/sata_vsc.c to only set the cache line size
to 0x80 if the default value is zero. Apparently zero isn't allowed
due to a bug in the chip, but I've found performance is much better
with the (non-zero) default instead of 0x80.
[note1: "default" means BIOS-programmed value, in this context -jgarzik]
[note2: superfluous braces were removed from the patch -jg]
Signed-off-by: Nate Dailey <nate.dailey@stratus.com>
Signed-off-by: Jeremy Higdon <jeremy@sgi.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/sata_vsc.c b/drivers/ata/sata_vsc.c
index 3d9daf2..2fd037b 100644
--- a/drivers/ata/sata_vsc.c
+++ b/drivers/ata/sata_vsc.c
@@ -346,6 +346,7 @@
struct ata_probe_ent *probe_ent;
void __iomem *mmio_base;
int rc;
+ u8 cls;
if (!printed_version++)
dev_printk(KERN_DEBUG, &pdev->dev, "version " DRV_VERSION "\n");
@@ -383,9 +384,12 @@
INIT_LIST_HEAD(&probe_ent->node);
/*
- * Due to a bug in the chip, the default cache line size can't be used
+ * Due to a bug in the chip, the default cache line size can't be
+ * used (unless the default is non-zero).
*/
- pci_write_config_byte(pdev, PCI_CACHE_LINE_SIZE, 0x80);
+ pci_read_config_byte(pdev, PCI_CACHE_LINE_SIZE, &cls);
+ if (cls == 0x00)
+ pci_write_config_byte(pdev, PCI_CACHE_LINE_SIZE, 0x80);
if (pci_enable_msi(pdev) == 0)
pci_intx(pdev, 0);