On Tuesday, July 28, 2015 01:51:21 PM Mika Westerberg wrote:
> Commit 20dacb71ad28 ("ACPI / PM: Rework device power management to follow
> ACPI 6") changed the device power management to use D3hot if the device
> in question does not have _PR3 method even if D3cold was requested by the
> caller.
>
> However, if the device has _PR3 device->power.state is also set to D3hot
> instead of D3Cold after power resources have been turned off because
> device->power.state will be assigned from "state" instead of
> "target_state".
>
> Next time the device is transitioned to D0, acpi_power_transition() will
> find that the current power state of the device is D3hot instead of D3cold
> which causes it to power down all resources required for the current
> (wrong) state D3hot.
>
> Below is a simplified ASL example of a real touch panel device which
> triggers the problem:
>
> Scope (TPL1)
> {
> Name (_PR0, Package (1) { \_SB.PCI0.I2C1.PXTC })
> Name (_PR3, Package (1) { \_SB.PCI0.I2C1.PXTC })
> ...
> }
>
> In both D0 and D3hot the same power resource is required. However, when
> acpi_power_transition() turns off power resources required for D3hot (as
> the device is transitioned to D0) it powers down PXTC which then makes the
> device to lose its power.
>
> Fix this by assigning "target_state" to the device power state instead of
> "state" that is always D3hot even for devices with valid _PR3.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Applied, thanks!
Rafael
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