• Hans de Goede's avatar
    i2c: core: ACPI: Properly set status byte to 0 for multi-byte writes · c463a158
    Hans de Goede authored
    acpi_gsb_i2c_write_bytes() returns i2c_transfer()'s return value, which
    is the number of transfers executed on success, so 1.
    
    The ACPI code expects us to store 0 in gsb->status for success, not 1.
    
    Specifically this breaks the following code in the Thinkpad 8 DSDT:
    
                ECWR = I2CW = ECWR /* \_SB_.I2C1.BAT0.ECWR */
                If ((ECST == Zero))
                {
                    ECRD = I2CR /* \_SB_.I2C1.I2CR */
                }
    
    Before this commit we set ECST to 1, causing the read to never happen
    breaking battery monitoring on the Thinkpad 8.
    
    This commit makes acpi_gsb_i2c_write_bytes() return 0 when i2c_transfer()
    returns 1, so the single write transfer completed successfully, and
    makes it return -EIO on for other (unexpected) return values >= 0.
    
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Acked-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
    Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
    c463a158
i2c-core-acpi.c 16.2 KB