[Nouveau] [Bug 98398] Acer Aspire V7-582PG (Haswell, GTX 750M) fails to power off GPU with runtime PM

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=98398

--- Comment #13 from Peter Wu <peter at lekensteyn.nl> ---
Created attachment 127942
  --> https://bugs.freedesktop.org/attachment.cgi?id=127942&action=edit
Disable d3cold on bridge when falling back to _DSM

The workaround patch has been merged in v4.9-rc3-34-gb0a6af8 (and backported to
4.8.7 via v4.8.6-109-g7290da4) but apparently it broke (system?) suspend/resume
according to the reporter.

Before the workaround patch:
 - _PR3 method is found, so nouveau assumes that PCI core takes care of D3cold.
 - Due to an ACPICA bug, PCI core fails to power off the device via runtime PM:
   https://bugs.acpica.org/show_bug.cgi?id=1333

After the workaround patch I guess that this happens:

 - _PR3 method is found, but unusable. Nouveau falls back to _DSM.
 - Due to the above ACPICA bug, the power resources not owned by any device. I
   guess that Linux then decides to power off the "unnecessary" power resource
   after system resume. (I saw something like this in a dmesg for a similiar
SSDT)
 - At this point I would guess that nouveau then follows the old DSM method,
but
   then I am confused because pcie_port_pm=off (or pre-4.8 kernels) supposedly
   have the same issue with this power resource.

If pcie_port_pm=off helps, then the attached patch should also work (no
pcie_port_pm=off needed). Can you give it a try on top of v4.8.7?

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