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Message-ID: <9ed62983bd03ed26cdb4399dd69b4096e8711fa9.camel@ljones.dev>
Subject: Re: [PATCH v3 6/6] asus-wmi: Support the hardware GPU MUX on some
 laptops
From:   Luke Jones <luke@ljones.dev>
To:     Hans de Goede <hdegoede@redhat.com>
Cc:     andy.shevchenko@gmail.com, pobrn@protonmail.com, pavel@ucw.cz,
        platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Fri, 12 Aug 2022 10:01:51 +1200
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References: <20220809025054.1626339-1-luke@ljones.dev>
         <20220809025054.1626339-7-luke@ljones.dev>
         <7365d41a-1475-118c-96a8-6ab927bda5b7@redhat.com>
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Hi Hans,

On Thu, 2022-08-11 at 15:53 +0200, Hans de Goede wrote:
> Hi,
>=20
> On 8/9/22 04:50, Luke D. Jones wrote:
> > Support the hardware GPU MUX switch available on some models. This
> > switch can toggle the MUX between:
> >=20
> > - 0, Dedicated mode
> > - 1, Optimus mode
> >=20
> > Optimus mode is the regular iGPU + dGPU available, while dedicated
> > mode switches the system to have only the dGPU available.
> >=20
> > Signed-off-by: Luke D. Jones <luke@ljones.dev>
>=20
> I see that you have replied to this that it needs more work.
>=20
> Besides it needing more work, ideally this should hook into
> the existing vga-switcheroo mechanism for this. Can you take
> a look at that please?
>=20
> I think this might be the first non GPU driver doing vga-
> switcheroo stuff. So this may be something to discuss
> on the dri-devel list.

I'm not sure how this would work. In typical ASUS fashion they do non-
standard stuff. This switch is a basic toggle that requires a reboot to
enable after writing to the ACPI method, after reboot the dGPU becomes
the only visible GPU on the system and (this GPU) can not be suspended.

In short: it toggles the laptop from discrete-only mode, and optimus
mode, requiring a reboot to switch.

From what I understand of switcheroo it is more to manage having dual
(or more) GPU available during runtime, and manage the power states,
offload etc.

I have a vastly improved patch for this prepared now. Because of how
the actual feature works (and the above explanation) it must be under
the asus-nb-wmi sysfs (next to the dgpu_disable and egpu_enable toggles
which are also unusual and non-standard work-arounds of Windows
issues).

Kind regards,
Luke.