Instead of writing 0xf blindly, preserve the content of write-once
PORTS_IMPL register over host resets.
This patch is taken from Jeff Garzik's AHCI init update patch.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
Cc: Jeff Garzik <jgarzik@xxxxxxxxx>
---
drivers/ata/ahci.c | 11 +++++++++--
1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 54e1f38..d268ced 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -563,11 +563,12 @@ static int ahci_deinit_port(void __iomem
static int ahci_reset_controller(void __iomem *mmio, struct pci_dev *pdev)
{
- u32 cap_save, tmp;
+ u32 cap_save, impl_save, tmp;
cap_save = readl(mmio + HOST_CAP);
cap_save &= ( (1<<28) | (1<<17) );
cap_save |= (1 << 27);
+ impl_save = readl(mmio + HOST_PORTS_IMPL);
/* global controller reset */
tmp = readl(mmio + HOST_CTL);
@@ -588,10 +589,16 @@ static int ahci_reset_controller(void __
return -EIO;
}
+ /* turn on AHCI mode */
writel(HOST_AHCI_EN, mmio + HOST_CTL);
(void) readl(mmio + HOST_CTL); /* flush */
+
+ /* These write-once registers are normally cleared on reset.
+ * Restore BIOS values... which we HOPE were present before
+ * reset.
+ */
writel(cap_save, mmio + HOST_CAP);
- writel(0xf, mmio + HOST_PORTS_IMPL);
+ writel(impl_save, mmio + HOST_PORTS_IMPL);
(void) readl(mmio + HOST_PORTS_IMPL); /* flush */
if (pdev->vendor == PCI_VENDOR_ID_INTEL) {
--
1.4.2.1
-
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
