linux-kernel - Re: [PATCH v2 1/2] PCI/ASPM: Override the ASPM and Clock PM states set by BIOS for devicetree platforms

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Message-ID: <aO-8aeJdvApesEqi@ryzen>
Date: Wed, 15 Oct 2025 17:23:21 +0200
From: Niklas Cassel <cassel@...nel.org>
To: Shawn Lin <shawn.lin@...k-chips.com>
Cc: Manivannan Sadhasivam <mani@...nel.org>,
	Bjorn Helgaas <helgaas@...nel.org>,
	manivannan.sadhasivam@....qualcomm.com,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Rob Herring <robh@...nel.org>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	"David E. Box" <david.e.box@...ux.intel.com>,
	Kai-Heng Feng <kai.heng.feng@...onical.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Chia-Lin Kao <acelan.kao@...onical.com>,
	Dragan Simic <dsimic@...jaro.org>,
	linux-rockchip@...ts.infradead.org, regressions@...ts.linux.dev,
	FUKAUMI Naoki <naoki@...xa.com>
Subject: Re: [PATCH v2 1/2] PCI/ASPM: Override the ASPM and Clock PM states
 set by BIOS for devicetree platforms

On Wed, Oct 15, 2025 at 09:00:41PM +0800, Shawn Lin wrote:
> For now, this is a acceptable option if default ASPM policy enable L1ss
> w/o checking if the HW could supports it... But how about adding
> supports-clkreq stuff to upstream host driver directly? That would help
> folks enable L1ss if the HW is ready and they just need adding property
> to the DT.

I like your idea, if you have time, please send a patch.

However, adding (working) support for L1 substates (via 'supports-clkreq')
is new code, and should thus be queued for next release instead of v6.18.

For now, pcie-dw-rockchip.c is broken for a lot of PCIe devices, so the
fix should be minimal and target v6.18, i.e. something like:
https://lore.kernel.org/linux-pci/20251015123142.392274-2-cassel@kernel.org/

Support for L1 substates via 'supports-clkreq' can be added on top of that
patch (while targeting v6.19).


Kind regards,
Niklas