linux-kernel - Re: [PATCH] x86/efistub: Add options for forcing Apple set

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Message-ID: <CAMj1kXEb9NPSwEr2brHYJtFQhnW55hoPycjcAgoPAfjU5ZFqZw@mail.gmail.com>
Date: Sun, 29 Dec 2024 19:22:07 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: Lukas Wunner <lukas@...ner.de>
Cc: Lleyton Gray <lleyton@...alabs.com>, gargaditya08@...e.com, 
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org
Subject: Re: [PATCH] x86/efistub: Add options for forcing Apple set_os protocol

On Sun, 29 Dec 2024 at 11:38, Lukas Wunner <lukas@...ner.de> wrote:
>
> On Sun, Dec 29, 2024 at 11:08:55AM +0100, Ard Biesheuvel wrote:
> > IIRC, the original issue is about not being able to use the discrete
> > GPU with the built-in panel, and the issue about an external GPU did
> > come up in the discussion - however, this does not affect the built-in
> > panel at all.
>
> The original issue was that the integrated GPU is hidden (powered off)
> unless the set_os protocol is used.  So only the discrete GPU is
> available, which results in terrible battery life.  Using set_os
> keeps the iGPU exposed so the OS can switch to it and power off
> the dGPU.
>

OK, thanks for clearing that up.

But this is distinctly different from the eGPU case we are dealing with here.

> We could have solved this by checking whether there are two PCI devices
> with VGA class in the system.  But that would have triggered in the
> iGPU + eGPU case.  We wanted to avoid that and thus quirked for the
> DMI product names instead.
>

Yeah, so it would be good to know what issue are trying to fix with this patch.