On Thu, Jul 28, 2016 at 11:51:11AM +0200, Jean Delvare wrote:
> Upstream commit: a7ae81952cdab56a1277bd2f9ed7284c0f575120
>
> Many Intel systems the BIOS declares a SystemIO OpRegion below the SMBus
> PCI device as can be seen in ACPI DSDT table from Lenovo Yoga 900:
>
> Device (SBUS)
> {
> OperationRegion (SMBI, SystemIO, (SBAR << 0x05), 0x10)
> Field (SMBI, ByteAcc, NoLock, Preserve)
> {
> HSTS, 8,
> Offset (0x02),
> HCON, 8,
> HCOM, 8,
> TXSA, 8,
> DAT0, 8,
> DAT1, 8,
> HBDR, 8,
> PECR, 8,
> RXSA, 8,
> SDAT, 16
> }
>
> There are also bunch of AML methods that that the BIOS can use to access
> these fields. Most of the systems in question AML methods accessing the
> SMBI OpRegion are never used.
>
> Now, because of this SMBI OpRegion many systems fail to load the SMBus
> driver with an error looking like one below:
>
> ACPI Warning: SystemIO range 0x0000000000003040-0x000000000000305F
> conflicts with OpRegion 0x0000000000003040-0x000000000000304F
> (\_SB.PCI0.SBUS.SMBI) (20160108/utaddress-255)
> ACPI: If an ACPI driver is available for this device, you should use
> it instead of the native driver
>
> The reason is that this SMBI OpRegion conflicts with the PCI BAR used by
> the SMBus driver.
>
> It turns out that we can install a custom SystemIO address space handler
> for the SMBus device to intercept all accesses through that OpRegion. This
> allows us to share the PCI BAR with the AML code if it for some reason is
> using it. We do not expect that this OpRegion handler will ever be called
> but if it is we print a warning and prevent all access from the SMBus
> driver itself.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=110041
> Reported-by: Andy Lutomirski <luto@xxxxxxxxxx>
> Reported-by: Pali Rohár <pali.rohar@xxxxxxxxx>
> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Reviewed-by: Jean Delvare <jdelvare@xxxxxxx>
> Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> Tested-by: Pali Rohár <pali.rohar@xxxxxxxxx>
> Tested-by: Jean Delvare <jdelvare@xxxxxxx>
> Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> This is a backport of upstream commit
> a7ae81952cdab56a1277bd2f9ed7284c0f575120 suitable for kernels v4.4 and
> v4.6. Thanks.
Sorry for being non-responsive - I was on vacation and just came back.
Thanks Jean for taking care of backporting this.
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html