[PATCH] i2c-i801: Fix resume when PEC is used

Fix for bug #6395:
Fail to resume on Tecra M2 with ADM1032 and Intel 82801DBM

The BIOS of the Tecra M2 doesn't like it when it has to reboot or
resume after the i2c-i801 driver has left the SMBus in PEC mode.
I have a more complete fix for 2.6.17 but the simple approach of
leaving the SMBus in non-PEC mode after every transaction should do
for -stable. That's what the i2c-i801 driver was doing up to 2.6.15
(inclusive).

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 8e0f3158215f6bc191864ef5f0a87f49ecc67bbd..dfca74933625e0c1c629778f0af1f9f8f00351b3 100644 (file)
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -478,6 +478,11 @@ static s32 i801_access(struct i2c_adapter * adap, u16 addr,
                ret = i801_transaction();
        }
 
+       /* Some BIOSes don't like it when PEC is enabled at reboot or resume
+          time, so we forcibly disable it after every transaction. */
+       if (hwpec)
+               outb_p(0, SMBAUXCTL);
+
        if(block)
                return ret;
        if(ret)