i2c-piix4: Increase the intitial delay for the ServerWorks CSB5

Per the PIIX4 errata, there maybe a delay between setting the
start bit in the Smbus Host Controller Register and the transaction
actually starting. If the driver doesn't delay long enough, it
may appear that the transaction is complete when actually it
hasn't started, this may lead to bus collisions.

While 1 ms appears to be enough for most chips, the ServerWorks CSB5
wants 2 ms.

Signed-off-by: David Milburn <dmilburn@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 12 insertions, 3 deletions

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index fdc9ad805e35..7217410f4251 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -104,6 +104,7 @@ MODULE_PARM_DESC(force_addr,
 static int piix4_transaction(void);
 
 static unsigned short piix4_smba;
+static int srvrworks_csb5_delay;
 static struct pci_driver piix4_driver;
 static struct i2c_adapter piix4_adapter;
 
@@ -122,6 +123,10 @@ static int __devinit piix4_setup(struct pci_dev *PIIX4_dev,
 
         dev_info(&PIIX4_dev->dev, "Found %s device\n", pci_name(PIIX4_dev));
 
+        if ((PIIX4_dev->vendor == PCI_VENDOR_ID_SERVERWORKS) &&
+            (PIIX4_dev->device == PCI_DEVICE_ID_SERVERWORKS_CSB5))
+                srvrworks_csb5_delay = 1;
+
         /* Don't access SMBus on IBM systems which get corrupted eeproms */
         if (dmi_check_system(piix4_dmi_table) &&
                         PIIX4_dev->vendor == PCI_VENDOR_ID_INTEL) {
@@ -230,10 +235,14 @@ static int piix4_transaction(void)
         outb_p(inb(SMBHSTCNT) | 0x040, SMBHSTCNT);
 
         /* We will always wait for a fraction of a second! (See PIIX4 docs errata) */
-        do {
+        if (srvrworks_csb5_delay) /* Extra delay for SERVERWORKS_CSB5 */
+                msleep(2);
+        else
+                msleep(1);
+
+        while ((timeout++ < MAX_TIMEOUT) &&
+               ((temp = inb_p(SMBHSTSTS)) & 0x01))
                 msleep(1);
-                temp = inb_p(SMBHSTSTS);
-        } while ((temp & 0x01) && (timeout++ < MAX_TIMEOUT));
 
         /* If the SMBus is still busy, we give up */
         if (timeout >= MAX_TIMEOUT) {