Re: hotplug works, but newly plug not

[Tejun Heo <htejun@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1379 bytes --]

Ming Zhang wrote:
> Hi All
> 
> I use the libata patch from
> http://home-tj.org/wiki/index.php/Libata-tj-stable with my supermicro MB
> ( ICH7R chip). The AHCI works as desired in most of the time.
> 
> If I have disk(s) plugged in during boot. Then after boot, I kept unplug
> and plug many times and it works fine.
> 
> but i noticed that if I have the disk(s) unplugged during boot, then
> after boot, I plug the disk and nothing shows. if I try to do rescan by
> run the rescan lun script, i saw these from dmesg.
> 
> Anything clue ? Thanks!
> 
> Ming
> 
> ---------------------------------------
> ata4: soft resetting port
> ata4: SATA link down (SStatus 0 SControl 0)
> ata4: EH complete
> ata3: soft resetting port
> ata3: SATA link down (SStatus 0 SControl 0)
> ata3: EH complete
> ata4: soft resetting port
> ata4: SATA link down (SStatus 0 SControl 0)
> ata4: EH complete
> ata3: soft resetting port
> ata3: SATA link down (SStatus 0 SControl 0)
> ata3: EH complete
> ata4: soft resetting port
> ata4: SATA link down (SStatus 0 SControl 0)
> ata4: EH complete

Hello,

That never happened to me on AHCI mode but I experienced similar thing 
with piix mode.  It might be that your BIOS doesn't turn on PCS enable 
bits for empty ports and thus the empty ports cannot be used after boot. 
Can you try the attached patch?  (only compile-tested, be cautious)

-- 
tejun

[-- Attachment #2: patch --]
[-- Type: text/plain, Size: 568 bytes --]

diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 45fd71d..83751dd 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -1306,6 +1306,15 @@ static int ahci_init_one (struct pci_dev
 		have_msi = 0;
 	}
 
+	{
+		u8 orig_pcs, pcs;
+		pci_read_config_byte(pdev, 0x92, &orig_pcs);
+		pci_write_config_byte(pdev, 0x92, 0xf);
+		pci_read_config_byte(pdev, 0x92, &pcs);
+		dev_printk(KERN_INFO, &pdev->dev, "pcs 0x%x->0x%x\n",
+			   orig_pcs, pcs);
+	}
+
 	probe_ent = kmalloc(sizeof(*probe_ent), GFP_KERNEL);
 	if (probe_ent == NULL) {
 		rc = -ENOMEM;