Some FSC hardware monitoring chips (Syleus at least) doesn't like quick writes we typically use to probe for I2C chips. Use a regular byte read instead for the address they live at (0x73). These are the only known chips living at this address on PC systems. For clarity, this fix should not be needed for kernels 2.6.30 and later, as we started instantiating the hwmon devices explicitly based on DMI data. Still, this fix is valuable in the following two cases: * Support for recent FSC chips on older kernels. The DMI-based device instantiation is more difficult to backport than the device support itself. * Case where the DMI-based device instantiation fails, whatever the reason. We fall back to probing in that case, so it should work. This fixes kernel bug #15634: https://bugzilla.kernel.org/show_bug.cgi?id=15634 Signed-off-by: Jean Delvare <khali@xxxxxxxxxxxx> Cc: stable@xxxxxxxxxx Cc: Hans de Goede <hdegoede@xxxxxxxxxx> --- drivers/i2c/i2c-core.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) --- linux-2.6.34-rc3.orig/drivers/i2c/i2c-core.c 2010-04-07 09:03:30.000000000 +0200 +++ linux-2.6.34-rc3/drivers/i2c/i2c-core.c 2010-04-07 13:45:28.000000000 +0200 @@ -1264,12 +1264,23 @@ static int i2c_detect_address(struct i2c return 0; /* Make sure there is something at this address */ - if (i2c_smbus_xfer(adapter, addr, 0, 0, 0, I2C_SMBUS_QUICK, NULL) < 0) - return 0; + if (addr == 0x73 && (adapter->class & I2C_CLASS_HWMON)) { + /* Special probe for FSC hwmon chips */ + union i2c_smbus_data dummy; + + if (i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_READ, 0, + I2C_SMBUS_BYTE_DATA, &dummy) < 0) + return 0; + } else { + if (i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_WRITE, 0, + I2C_SMBUS_QUICK, NULL) < 0) + return 0; - /* Prevent 24RF08 corruption */ - if ((addr & ~0x0f) == 0x50) - i2c_smbus_xfer(adapter, addr, 0, 0, 0, I2C_SMBUS_QUICK, NULL); + /* Prevent 24RF08 corruption */ + if ((addr & ~0x0f) == 0x50) + i2c_smbus_xfer(adapter, addr, 0, I2C_SMBUS_WRITE, 0, + I2C_SMBUS_QUICK, NULL); + } /* Finally call the custom detection function */ memset(&info, 0, sizeof(struct i2c_board_info)); -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
