On Thu, Aug 23, 2018 at 11:45:53AM +0300, Mika Westerberg wrote:
> 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=200737
> Reported-by: Yussuf Khalil <dev@xxxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
I'll give Jean a few more days to comment but will apply it for -rc2
latest.
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