linux-kernel - Re: [PATCH 0/2] PCI/ASPM: Avoid L0s and L1 on Sophgo 2042/2044 PCIe Root Ports

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Message-ID: <yko2amyugikkuo2fa4plmkghx3ygxlzjw5nmerw4jl5ah6jyi5@qos2t2y356ot>
Date: Tue, 30 Dec 2025 15:38:11 +0530
From: Manivannan Sadhasivam <mani@...nel.org>
To: Inochi Amaoto <inochiama@...il.com>
Cc: Bjorn Helgaas <helgaas@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, Chen Wang <unicorn_wang@...look.com>, 
	Han Gao <rabenda.cn@...il.com>, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yixun Lan <dlan@...too.org>, Longbin Li <looong.bin@...il.com>
Subject: Re: [PATCH 0/2] PCI/ASPM: Avoid L0s and L1 on Sophgo 2042/2044 PCIe
 Root Ports

On Tue, Dec 30, 2025 at 05:45:39PM +0800, Inochi Amaoto wrote:
> On Fri, Dec 26, 2025 at 10:30:31AM -0600, Bjorn Helgaas wrote:
> > On Thu, Dec 25, 2025 at 06:05:27PM +0800, Inochi Amaoto wrote:
> > > Since commit f3ac2ff14834 ("PCI/ASPM: Enable all ClockPM and ASPM
> > > states for devicetree platforms") force enable ASPM on all device tree
> > > platform, the SG2042/SG2044 PCIe Root Ports breaks as it advertises L0s
> > > and L1 capabilities without supporting it.
> > > 
> > > Override the L0s and L1 Support advertised in Link Capabilities by the
> > > SG2042/SG2044 Root Ports so we don't try to enable those states.
> > > 
> > > Inochi Amaoto (2):
> > >   PCI/ASPM: Avoid L0s and L1 on Sophgo 2042 PCIe [1f1c:2042] Root Ports
> > >   PCI/ASPM: Avoid L0s and L1 on Sophgo 2044 PCIe [1f1c:2044] Root Ports
> > > 
> > >  drivers/pci/quirks.c    | 2 ++
> > >  include/linux/pci_ids.h | 2 ++
> > >  2 files changed, 4 insertions(+)
> > 
> > 1) Can somebody at Sophgo confirm that this is a hardware erratum?  I
> > just want to make rule out some kind of OS bug in configuring L0s/L1.
> > 
> 
> Hi Bjorn,
> 
> I have asked for the Sophgo staff, and they already confirmed this 
> hardware errata.
> 

Okay. If the hardware (Root Port) doesn't support L0s and L1, you should disable
the capability in the sophgo controller driver instead. You can use this as a
reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/pci/controller/dwc/pcie-qcom.c#n331

Quirks is mostly meant for PCI endpoint devices (sometimes Root Ports also if
there is no host controller driver).

- Mani

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