From: Lukas Wunner <lukas@wunner.de>
To: "Deucher, Alexander" <Alexander.Deucher@amd.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
"Limonciello, Mario" <Mario.Limonciello@amd.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Andreas Noever <andreas.noever@gmail.com>,
"open list:PCI SUBSYSTEM" <linux-pci@vger.kernel.org>,
"open list:THUNDERBOLT DRIVER" <linux-usb@vger.kernel.org>,
Michael Jamet <michael.jamet@intel.com>,
Yehezkel Bernat <YehezkelShB@gmail.com>
Subject: Re: [PATCH 0/2] Mark USB4 controllers as is_thunderbolt
Date: Mon, 7 Feb 2022 18:47:03 +0100 [thread overview]
Message-ID: <20220207174703.GA25761@wunner.de> (raw)
In-Reply-To: <BL1PR12MB51442184B407A747E4C487F1F72C9@BL1PR12MB5144.namprd12.prod.outlook.com>
On Mon, Feb 07, 2022 at 03:52:13PM +0000, Deucher, Alexander wrote:
> > From: Mika Westerberg <mika.westerberg@linux.intel.com>
> > The other option is to look for ACPI companion (ACPI_COMPANION()) of the
> > device. AFAICT dGPUs don't have one (as the BIOS does not know in advance
> > what will be connected to the hotplug ports) whereas internal does typically
> > have one.
>
> Yeah, this is probably the right way to do this.
No, that doesn't work. At least Apple represents the first few devices
in the Thunderbolt daisy-chain in the ACPI namespace, so IIUC you'd find
an ACPI companion for those but not for the remainder of the daisy-chain.
This is from a 2019/2020 MacBookPro16,1:
$ grep 'Device ' acpidump/mbp161/ssdt6.dsl
Device (UPSB)
Device (DSB0)
Device (NHI0)
Device (DSB1)
Device (UPS0)
Device (DSB0)
Device (DEV0)
Device (DSB3)
Device (UPS0)
Device (DSB0)
Device (DEV0)
Device (DSB3)
Device (DEV0)
...
There's a *reason* why I introduced the is_thunderbolt flag,
there is no other reliable way to detect externally attached devices.
Thanks,
Lukas
next prev parent reply other threads:[~2022-02-07 18:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 18:28 [PATCH 0/2] Mark USB4 controllers as is_thunderbolt Mario Limonciello
2022-02-04 18:28 ` [PATCH 1/2] thunderbolt: move definition of PCI_CLASS_SERIAL_USB_USB4 Mario Limonciello
2022-02-04 18:28 ` [PATCH 2/2] pci: mark USB4 devices as "is_thunderbolt" Mario Limonciello
2022-02-04 22:29 ` Bjorn Helgaas
2022-02-05 9:39 ` Lukas Wunner
2022-02-04 18:36 ` [PATCH 0/2] Mark USB4 controllers as is_thunderbolt Deucher, Alexander
2022-02-07 6:41 ` Mika Westerberg
2022-02-07 15:00 ` Deucher, Alexander
2022-02-07 15:45 ` Mika Westerberg
2022-02-07 15:52 ` Deucher, Alexander
2022-02-07 17:47 ` Lukas Wunner [this message]
2022-02-08 6:33 ` Mika Westerberg
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