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

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Message-ID: <Z3EmoNWbkbYZ7NZO@wunner.de>
Date: Sun, 29 Dec 2024 11:38:24 +0100
From: Lukas Wunner <lukas@...ner.de>
To: Ard Biesheuvel <ardb@...nel.org>
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, 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.

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.

Thanks,

Lukas