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From: Lukas Wunner <lukas@wunner.de>
To: Orlando Chamberlain <orlandoch.dev@gmail.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Mark Gross <markgross@kernel.org>,
	platform-driver-x86@vger.kernel.org,
	linux-kernel@vger.kernel.org, Seth Forshee <sforshee@kernel.org>,
	Aditya Garg <gargaditya08@live.com>,
	Aun-Ali Zaidi <admin@kodeit.net>,
	Kerem Karabay <kekrby@gmail.com>
Subject: Re: [PATCH v3 4/5] apple-gmux: support MMIO gmux on T2 Macs
Date: Mon, 20 Feb 2023 10:20:48 +0100	[thread overview]
Message-ID: <20230220092048.GA25532@wunner.de> (raw)
In-Reply-To: <20230218132007.3350-5-orlandoch.dev@gmail.com>

On Sun, Feb 19, 2023 at 12:20:06AM +1100, Orlando Chamberlain wrote:
> --- a/drivers/platform/x86/apple-gmux.c
> +++ b/drivers/platform/x86/apple-gmux.c
> @@ -28,15 +28,17 @@
>   * DOC: Overview
>   *
>   * gmux is a microcontroller built into the MacBook Pro to support dual GPUs:
> - * A `Lattice XP2`_ on pre-retinas, a `Renesas R4F2113`_ on retinas.
> + * A `Lattice XP2`_ on pre-retinas, a `Renesas R4F2113`_ on pre-T2 retinas.
> + * The chip used on T2 Macs is not known.

I've just taken a look at the schematics of the MBP16,1 and it turns out
that T2 *is* the gmux.  The chip is called H9M.  The interaction with the
OS is through that MMIO area.

There's a GPIO expander attached to T2 via I2C (NXP PCAL6524), probably
because they didn't have enough GPIO pins available on T2 itself.
The GPIO expander enables/disables the voltage regulators of the discrete
GPU, hence can cut power to it.  It also drives panel power and has a GPIO
to switch the mux.

The mux is an NXP CBTL06142 as on previous models.

Thanks,

Lukas

  reply	other threads:[~2023-02-20  9:20 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-18 13:20 [PATCH v3 0/5] apple-gmux: support MMIO gmux type on T2 Macs Orlando Chamberlain
2023-02-18 13:20 ` [PATCH v3 1/5] apple-gmux: use first bit to check switch state Orlando Chamberlain
2023-02-18 13:20 ` [PATCH v3 2/5] apple-gmux: refactor gmux types Orlando Chamberlain
2023-02-18 13:20 ` [PATCH v3 3/5] apple-gmux: Use GMSP acpi method for interrupt clear Orlando Chamberlain
2023-02-19 22:17   ` Lukas Wunner
2023-02-20 12:02     ` Orlando Chamberlain
2023-02-18 13:20 ` [PATCH v3 4/5] apple-gmux: support MMIO gmux on T2 Macs Orlando Chamberlain
2023-02-20  9:20   ` Lukas Wunner [this message]
2023-02-20 12:16     ` Orlando Chamberlain
2023-02-18 13:20 ` [PATCH v3 5/5] apple-gmux: add debugfs interface Orlando Chamberlain
2023-03-01 12:54 ` [PATCH v3 0/5] apple-gmux: support MMIO gmux type on T2 Macs Hans de Goede
2023-03-03  7:54   ` Orlando Chamberlain

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