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Date: Mon, 27 Oct 2025 17:35:17 -0500
From: Bjorn Helgaas <helgaas@kernel.org>
To: Johan Hovold <johan@kernel.org>
Cc: Manivannan Sadhasivam <mani@kernel.org>, linux-pci@vger.kernel.org,
	Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>,
	Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kwilczynski@kernel.org>,
	Frank Li <Frank.li@nxp.com>, Shawn Lin <shawn.lin@rock-chips.com>,
	Rob Herring <robh@kernel.org>,
	"David E . Box" <david.e.box@linux.intel.com>,
	Kai-Heng Feng <kai.heng.feng@canonical.com>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Chia-Lin Kao <acelan.kao@canonical.com>,
	Gustavo Pimentel <Gustavo.Pimentel@synopsys.com>,
	Han Jingoo <jingoohan1@gmail.com>,
	Bjorn Andersson <andersson@kernel.org>,
	Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>,
	Bartosz Golaszewski <brgl@bgdev.pl>, linux-arm-msm@vger.kernel.org,
	linux-kernel@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>
Subject: Re: [PATCH] Revert "PCI: qcom: Remove custom ASPM enablement code"
Message-ID: <20251027223517.GA1484052@bhelgaas>
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In-Reply-To: <aP9Ed1Y1lcayFn7Q@hovoldconsulting.com>

On Mon, Oct 27, 2025 at 11:07:51AM +0100, Johan Hovold wrote:
> On Sun, Oct 26, 2025 at 02:37:54PM -0500, Bjorn Helgaas wrote:
> > On Sun, Oct 26, 2025 at 08:58:29PM +0530, Manivannan Sadhasivam wrote:
> 
> > As far as I know, it's L1SS that has catastrophic effects.  I haven't
> > seen anything for L0s or L1.
> 
> Enabling L0s unconditionally certainly blew up on some Qualcomm
> machines. See commit d1997c987814 ("PCI: qcom: Disable ASPM L0s for
> sc8280xp, sa8540p and sa8295p").

Ah, right, thanks for that reminder.

IIUC the qcom_pcie_clear_aspm_l0s() quirk that removes L0s from the
advertised Link Capabilities is still there and prevents df5192d9bb0e
("PCI/ASPM: Enable only L0s and L1 for devicetree platforms") from
being a problem on those platforms, right?