[PATCH] i2c driver changes 2.6.0-test3

Greg KH
2003-08-15T18:36:47Z

ChangeSet 1.1123.18.1, 2003/08/11 14:36:10-07:00, trini@kernel.crashing.org

[PATCH] I2C: Fix for i2c-piix4 with on some boards

Hello all. On some boards with an Intel PIIX4 the BIOS (such as the one
found on a Force CPCI-735) will incorrectly configure the chipset, and
leaves a register in an undefined state causing i2c to behave strangley.
The following patches (first vs lm_sensors-2.8.0 and then vs
2.6.0-test3) fixes the issue.

drivers/i2c/busses/i2c-piix4.c | 9 +++++++++
1 files changed, 9 insertions(+)

diff -Nru a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
--- a/drivers/i2c/busses/i2c-piix4.c Fri Aug 15 11:27:13 2003
+++ b/drivers/i2c/busses/i2c-piix4.c Fri Aug 15 11:27:13 2003
@@ -160,6 +160,15 @@
}

pci_read_config_byte(PIIX4_dev, SMBHSTCFG, &temp);
+
+ /* Some BIOS will set up the chipset incorrectly and leave a register
+ in an undefined state (causing I2C to act very strangely). */
+ if (temp & 0x02) {
+ printk("Fixed I2C problem on Force CPCI735\n");
+ temp = temp & 0xfd;
+ pci_write_config_byte(PIIX4_dev, SMBHSTCFG, temp);
+ }
+
/* If force_addr is set, we program the new address here. Just to make
sure, we disable the PIIX4 first. */
if (force_addr) {