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ata_piix: verify SIDPR access before enabling it

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On certain configurations (certain macbooks), even though all the
conditions for SIDPR access described in the datasheet are met,
actually reading those registers just returns 0 and have no effect on
write.  Verify SIDPR is actually working before enabling it.

This is reported by Ryan Roth in bz#10512.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Ryan Roth <ryan.roth@ch2m.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Tejun Heo 2008-05-01 10:03:08 +09:00 committed by Jeff Garzik
parent 78ab88f04f
commit cb6716c879
1 changed files with 25 additions and 0 deletions
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25
drivers/ata/ata_piix.c
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@ -1348,6 +1348,8 @@ 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 */
@ -1366,6 +1368,29 @@ 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;
}