linux-kernel - Re: [PATCH 2/2] PCI: Ignore PCIe ports used for tunneling in pcie_bandwidth

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Message-ID: <bb4d8fad-dced-4fed-9582-2db50643e868@amd.com>
Date:   Thu, 2 Nov 2023 10:26:31 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     Lukas Wunner <lukas@...ner.de>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, bhelgaas@...gle.com,
        mika.westerberg@...ux.intel.com, andreas.noever@...il.com,
        michael.jamet@...el.com, YehezkelShB@...il.com,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, Alexander.Deucher@....com
Subject: Re: [PATCH 2/2] PCI: Ignore PCIe ports used for tunneling in
 pcie_bandwidth_available()

On 11/2/2023 10:21, Lukas Wunner wrote:
> On Wed, Nov 01, 2023 at 08:14:31PM -0500, Mario Limonciello wrote:
>> Considering this I think it's a good idea to move that creation of the
>> device link into drivers/pci/pci-acpi.c and store a bit in struct pci_device
>> to indicate it's a tunneled port.
>>
>> Then 'thunderbolt' can look for this directly instead of walking all the FW
>> nodes.
>>
>> pcie_bandwidth_available() can just look at the tunneled port bit instead of
>> the existence of the device link.
> 
> pci_is_thunderbolt_attached() should already be doing exactly what
> you want to achieve with the new bit.  It tells you whether a PCI
> device is behind a Thunderbolt tunnel.  So I don't think a new bit
> is actually needed.
> 
> Thanks,
> 
> Lukas

It's only for a device connected to an Intel TBT3 controller though; it 
won't apply to USB4.