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Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines.

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On Mon, Mar 14, 2016 at 11:23 AM, Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
> On Mon, Mar 14, 2016 at 07:47:39PM +1000, Dave Airlie wrote:
>> >
>> >> -     if (pcie_port_runtime_suspend_allowed(dev))
>> >> +     if (pcie_port_runtime_suspend_allowed(dev)) {
>> >> +             pm_runtime_allow(&dev->dev);
>> >
>> > PCI drivers typically have left this decision up to the userspace. I'm
>> > wondering whether it is good idea to deviate from that here? Of course
>> > this allows immediate power savings but could potentially cause problems
>> > as well.
>> >
>>
>> No distro has ever shipped userspace to do this, I really think this
>> is a bad design.
>> We have wasted countless watts of power on this stupid idea that people will
>> run powertop, only a few people in the world run powertop, lots of
>> people use Linux.
>
> That is a fair point.
>
> I do not have anything against calling pm_runtime_allow() here. In fact
> we already do the same in Intel LPSS drivers. I just wanted to bring
> that up.
>
> Rafael, what do you think?

We can do that to start with.  If there are no problems in the field
with it, I don't see any problems in principle.

> If we anyway are going to add cut-off date to enable runtime PM we
> should expect that the hardware is also capable of doing so (and if not
> we can always blacklist the exceptions).

Sounds reasonable.

>> The kernel should power stuff down not wait for the user to run powertop,
>> At least for the GPU it's in the area of 8W of power, and I've got the
>> GPU drivers doing this themselves,
>>
>> I could have the GPU driver call runtime allow for it's host bridge I suppose,
>> if we insist on the userspace cares, but I'd prefer not doing so.
>>
>> > I think we need to add corresponding call to pm_runtime_forbid() in
>> > pcie_portdrv_remove().
>>
>> Yes most likely.
>
> BTW, I can add both calls to the next version of PCIe runtime PM patches
> if you are OK with that, and all agree this is a good idea.

That would be fine by me.

Thanks,
Rafael

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[PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Dave Airlie <airlied@gmail.com> - 2016-03-09 07:20 +0100
  Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-09 14:20 +0100
    Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Dave Airlie <airlied@gmail.com> - 2016-03-09 23:00 +0100
      Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-10 22:00 +0100
        Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Mika Westerberg <mika.westerberg@linux.intel.com> - 2016-03-11 12:00 +0100
          Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-03-11 14:50 +0100
            Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Dave Airlie <airlied@gmail.com> - 2016-03-14 03:20 +0100
              Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Dave Airlie <airlied@gmail.com> - 2016-03-14 10:50 +0100
                Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Daniel Vetter <daniel@ffwll.ch> - 2016-03-14 11:10 +0100
                Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Mika Westerberg <mika.westerberg@linux.intel.com> - 2016-03-14 11:30 +0100
                Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. "Rafael J. Wysocki" <rafael@kernel.org> - 2016-03-14 14:00 +0100
                Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Mika Westerberg <mika.westerberg@linux.intel.com> - 2016-03-14 15:40 +0100
              Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Mika Westerberg <mika.westerberg@linux.intel.com> - 2016-03-14 10:50 +0100
                Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Lukas Wunner <lukas@wunner.de> - 2016-03-15 14:40 +0100
                Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Mika Westerberg <mika.westerberg@linux.intel.com> - 2016-03-15 15:00 +0100
              Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Alex Deucher <alexdeucher@gmail.com> - 2016-03-14 15:40 +0100
  Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Lukas Wunner <lukas@wunner.de> - 2016-03-09 15:40 +0100
    Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Alex Deucher <alexdeucher@gmail.com> - 2016-03-09 18:00 +0100
      Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10  machines. Lukas Wunner <lukas@wunner.de> - 2016-03-09 21:20 +0100
        Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Alex Deucher <alexdeucher@gmail.com> - 2016-03-09 21:30 +0100
        Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Dave Airlie <airlied@gmail.com> - 2016-03-09 23:10 +0100
    Re: [PATCH 1/2] vga_switcheroo: add power support for windows 10 machines. Dave Airlie <airlied@gmail.com> - 2016-03-09 23:10 +0100

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