From b1d4b390ea4bb480e65974ce522a04022608a8df Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Tue, 4 May 2010 11:09:28 +0200 Subject: [PATCH] i2c: Fix probing of FSC hardware monitoring chips 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 Acked-by: Hans de Goede Cc: stable@kernel.org --- drivers/i2c/i2c-core.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index b9306b1a6baa..5105126225c3 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -1264,12 +1264,23 @@ static int i2c_detect_address(struct i2c_client *temp_client, 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; - /* Prevent 24RF08 corruption */ - if ((addr & ~0x0f) == 0x50) - i2c_smbus_xfer(adapter, addr, 0, 0, 0, I2C_SMBUS_QUICK, NULL); + 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, I2C_SMBUS_WRITE, 0, + I2C_SMBUS_QUICK, NULL); + } /* Finally call the custom detection function */ memset(&info, 0, sizeof(struct i2c_board_info));