ata_piix: verify SIDPR access before enabling it

[karo-tx-linux.git] / drivers / ata / ata_piix.c

diff --git a/drivers/ata/ata_piix.c b/drivers/ata/ata_piix.c
index fae8404254c022dcaba09085eedfc9864657fa78..815b8c3b987106bccea5b72f44778be3567a696b 100644 (file)
--- a/drivers/ata/ata_piix.c
+++ b/drivers/ata/ata_piix.c
@@ -1531,6 +1531,8 @@ static void __devinit piix_init_sidpr(struct ata_host *host)
 {
        struct pci_dev *pdev = to_pci_dev(host->dev);
        struct piix_host_priv *hpriv = host->private_data;
+       struct ata_device *dev0 = &host->ports[0]->link.device[0];
+       u32 scontrol;
        int i;
 
        /* check for availability */
@@ -1549,6 +1551,29 @@ static void __devinit piix_init_sidpr(struct ata_host *host)
                return;
 
        hpriv->sidpr = pcim_iomap_table(pdev)[PIIX_SIDPR_BAR];
+
+       /* SCR access via SIDPR doesn't work on some configurations.
+        * Give it a test drive by inhibiting power save modes which
+        * we'll do anyway.
+        */
+       scontrol = piix_sidpr_read(dev0, SCR_CONTROL);
+
+       /* if IPM is already 3, SCR access is probably working.  Don't
+        * un-inhibit power save modes as BIOS might have inhibited
+        * them for a reason.
+        */
+       if ((scontrol & 0xf00) != 0x300) {
+               scontrol |= 0x300;
+               piix_sidpr_write(dev0, SCR_CONTROL, scontrol);
+               scontrol = piix_sidpr_read(dev0, SCR_CONTROL);
+
+               if ((scontrol & 0xf00) != 0x300) {
+                       dev_printk(KERN_INFO, host->dev, "SCR access via "
+                                  "SIDPR is available but doesn't work\n");
+                       return;
+               }
+       }
+
        host->ports[0]->ops = &piix_sidpr_sata_ops;
        host->ports[1]->ops = &piix_sidpr_sata_ops;
 }