• Mika Westerberg's avatar
    i2c: i801: Allow ACPI AML access I/O ports not reserved for SMBus · 7fd6d98b
    Mika Westerberg authored
    Commit 7ae81952cda ("i2c: i801: Allow ACPI SystemIO OpRegion to conflict
    with PCI BAR") made it possible for AML code to access SMBus I/O ports
    by installing custom SystemIO OpRegion handler and blocking i80i driver
    access upon first AML read/write to this OpRegion.
    
    However, while ThinkPad T560 does have SystemIO OpRegion declared under
    the SMBus device, it does not access any of the SMBus registers:
    
        Device (SMBU)
        {
            ...
    
            OperationRegion (SMBP, PCI_Config, 0x50, 0x04)
            Field (SMBP, DWordAcc, NoLock, Preserve)
            {
                ,   5,
                TCOB,   11,
                Offset (0x04)
            }
    
            Name (TCBV, 0x00)
            Method (TCBS, 0, NotSerialized)
            {
                If ((TCBV == 0x00))
                {
                TCBV = (\_SB.PCI0.SMBU.TCOB << 0x05)
                }
    
                Return (TCBV) /* \_SB_.PCI0.SMBU.TCBV */
            }
    
            OperationRegion (TCBA, SystemIO, TCBS (), 0x10)
            Field (TCBA, ByteAcc, NoLock, Preserve)
            {
                Offset (0x04),
                ,   9,
                CPSC,   1
            }
        }
    
    Problem with the current approach is that it blocks all I/O port access
    and because this system has touchpad connected to the SMBus controller
    after first AML access (happens during suspend/resume cycle) the
    touchpad fails to work anymore.
    
    Fix this so that we allow ACPI AML I/O port access if it does not touch
    the region reserved for the SMBus.
    
    Fixes: 7ae81952cda ("i2c: i801: Allow ACPI SystemIO OpRegion to conflict with PCI BAR")
    Link: https://bugzilla.kernel.org/show_bug.cgi?id=200737Reported-by: default avatarYussuf Khalil <dev@pp3345.net>
    Signed-off-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
    Reviewed-by: default avatarJean Delvare <jdelvare@suse.de>
    Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
    7fd6d98b
i2c-i801.c 51.7 KB