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Date: Tue, 2 Jan 2024 18:12:37 -0600
From: Bjorn Helgaas <helgaas@kernel.org>
To: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Michael Schaller <michael@5challer.de>,
	Kai-Heng Feng <kai.heng.feng@canonical.com>,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	regressions@lists.linux.dev,
	"Maciej W . Rozycki" <macro@orcam.me.uk>,
	Ajay Agarwal <ajayagarwal@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Johan Hovold <johan+linaro@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>, stable@vger.kernel.org
Subject: Re: [PATCH] Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()"
Message-ID: <20240103001237.GA1755171@bhelgaas>
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In-Reply-To: <20cd835e-f84c-4c43-812e-6706f7266150@linux.intel.com>

On Tue, Jan 02, 2024 at 03:33:51PM -0800, Kuppuswamy Sathyanarayanan wrote:
> On 1/2/2024 3:25 PM, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@google.com>
> > 
> > This reverts commit 08d0cc5f34265d1a1e3031f319f594bd1970976c.
> > 
> > Michael reported that when attempting to resume from suspend to RAM on ASUS
> > mini PC PN51-BB757MDE1 (DMI model: MINIPC PN51-E1), 08d0cc5f3426
> > ("PCI/ASPM: Remove pcie_aspm_pm_state_change()") caused a 12-second delay
> > with no output, followed by a reboot.
> > 
> > Workarounds include:
> > 
> >   - Reverting 08d0cc5f3426 ("PCI/ASPM: Remove pcie_aspm_pm_state_change()")
> >   - Booting with "pcie_aspm=off"
> >   - Booting with "pcie_aspm.policy=performance"
> >   - "echo 0 | sudo tee /sys/bus/pci/devices/0000:03:00.0/link/l1_aspm"
> >     before suspending
> >   - Connecting a USB flash drive
> 
> Did you find the root cause? Is this issue specific to that particular
> device? If yes, can we do a quirk?

Unfortunately we don't know the root cause yet.  Without knowing the
root cause, I don't think we can make a good quirk.

Bjorn