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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - Acer Aspire V7-582PG (Haswell, GTX 750M) fails to power off GPU with runtime PM"
href="https://bugs.freedesktop.org/show_bug.cgi?id=98398#c11">Comment # 11</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - Acer Aspire V7-582PG (Haswell, GTX 750M) fails to power off GPU with runtime PM"
href="https://bugs.freedesktop.org/show_bug.cgi?id=98398">bug 98398</a>
from <span class="vcard"><a class="email" href="mailto:peter@lekensteyn.nl" title="Peter Wu <peter@lekensteyn.nl>"> <span class="fn">Peter Wu</span></a>
</span></b>
<pre>So 4.7 and before used the "DSM" method on runtime-suspend:
- \_SB.PCI0.RP05.PEGP._DSM would be invoked to enable Optimus
- \_SB.PCI0.RP05.PEGP._PS3 is then invoked which would enter D3cold
(note, this method is still used in 4.8 on older laptops or with the
pcie_pm_port=off kernel option)
Since 4.8, _DSM is not called anymore by nouveau (when support from the PCI
core is detected) and this sequence should instead happen:
- \_SB.PCI0.RP05.PEGP._PS3 (does nothing besides updating _STA)
- PCIe core removes power for the PCIe port since all its children are in
D3 and are willing to transition to D3cold. It does so by invoking
\NVP3._OFF (where \NVP3 is the power resource from \_SB.PCI0.RP05._PR3)
That is how I think it should work in theory, but on Ricks laptop running
4.8.4,
/sys/bus/devices/0000:1c.4/firmware_node/ does not have power_resources_D0
devices (which I do have on my own laptop for 0000:01:0).
The SSDT1 of Rick's Acer laptop shows this structure:
If (\_OSI ("Windows 2013"))
{
Scope (\_SB.PCI0.RP05)
{
//...
Name (_PR0, Package (0x01) // _PR0: Power Resources for D0
{
NVP3
})
Name (_PR2, Package (0x01) // _PR2: Power Resources for D2
{
NVP2
})
Name (_PR3, Package (0x01) // _PR3: Power Resources for D3hot
{
NVP3
})
// ...
Method (_PS0, 0, NotSerialized) // _PS0: Power State 0
{
}
Method (_PS3, 0, NotSerialized) // _PS3: Power State 3
{
}
}
Name (MSD3, Zero)
PowerResource (NVP3, 0x00, 0x0000)
{
Name (_STA, One) // _STA: Status
// ...
Method (_ON, 0, NotSerialized) // _ON_: Power On
{
// ...
}
Method (_OFF, 0, NotSerialized) // _OFF: Power Off
{
// ...
}
}
The dmesg does show "ACPI: Power Resource [NVP3] (on)", so I guess that the
methods are found. It is a mystery to me why the "power_resources_Dx" files are
not created, possibly breaking PM.</pre>
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