[Nouveau] [PATCH v3 0/4] nouveau RPM fixes for Optimus (final)

[Ilia Mirkin]

On Fri, Jul 15, 2016 at 12:27 PM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Fri, Jul 15, 2016 at 12:10 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Fri, Jul 15, 2016 at 9:12 AM, Peter Wu <peter at lekensteyn.nl> wrote:
>>> Hi,
>>>
>>> Here are two patches to fix an issue reported on kernel bugzilla (infinite loop
>>> due to unchecked function) and a more important fix to fix hanging Optimus
>>> machines when runtime PM is enabled (with pm/pci patches).
>>>
>>> These are the final patches targeting v4.8. Changes compared to v2[1]:
>>> collected R-b from Hans and Mika and fixed a minor comment style issue.
>>>
>>> I recommend it to be merged before the pci/pm patches[2], otherwise there is a
>>> window where newer Nvidia Optimus laptops might fail to runtime resume and/or
>>> lock up.  Once the pci/pm branch is merged I will propose another patch to
>>> improve reliability[3].
>>>
>>> Known issue with patch 4: when a Nvidia HDMI audio function is present, the
>>> bridge will not suspend and hence the Nvidia card will still be powered. Fixing
>>
>> That's basically all optimus gpu's, right? Anything GT21x+ has a HDMI
>> audio subfunction, and prior to that, the nvidia gpu tended to be the
>> only gpu, or hard-muxed.
>
> I'd imagine there is a strap on the asic so the audio function is only
> enabled if there is a connector actually wired to the dGPU.  It
> doesn't make much sense to expose audio if there is no way to use it.

A lot of the time, there actually is a connector wired up. A lot of
the other time, there is no connector, but the display unit is still
there. Very recently, NVIDIA gpu's have started coming out marked as
"3d accelerator", which sometimes but not always means that there's no
display unit, and for those, I would assume there is no audio
subfunction.

However this is a fraction of all devices using runpm.

  -ilia