linux-kernel - Re: [PATCH v4] PCI: Prevent power state transition of erroneous device

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Message-ID: <aC3XiuOPVYB2EX18@wunner.de>
Date: Wed, 21 May 2025 15:39:22 +0200
From: Lukas Wunner <lukas@...ner.de>
To: Denis Benato <benato.denis96@...il.com>
Cc: Mario Limonciello <superm1@...nel.org>,
	Raag Jadav <raag.jadav@...el.com>, rafael@...nel.org,
	mahesh@...ux.ibm.com, oohall@...il.com, bhelgaas@...gle.com,
	linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, ilpo.jarvinen@...ux.intel.com,
	aravind.iddamsetty@...ux.intel.com
Subject: Re: [PATCH v4] PCI: Prevent power state transition of erroneous
 device

On Tue, May 20, 2025 at 07:22:04PM +0200, Denis Benato wrote:
> This is the very same exact kernel, minus the patch in question:
> https://pastebin.com/rwMYgG7C
> 
> Both previous kernel and this one have CONFIG_PCI_DEBUG=y.

This log excerpt shows that the ASMedia Thunderbolt controller
below the Intel Thunderbolt controller couldn't be enumerated
on boot:

mag 20 18:42:20 denis-pc kernel: pci 0000:03:01.0: broken device, retraining non-functional downstream link at 2.5GT/s
mag 20 18:42:20 denis-pc kernel: pci 0000:03:01.0: retraining failed

However, the Thunderbolt tunnel goes up and the devices are
enumerated 24 seconds later:

mag 20 18:42:44 denis-pc kernel: pcieport 0000:03:01.0: pciehp: Slot(1-1): Card present
mag 20 18:42:44 denis-pc kernel: pcieport 0000:03:01.0: pciehp: Slot(1-1): Link Up

Thanks,

Lukas