linux-kernel - Re: [PATCH v4 08/11] PCI: qcom: Add support for PCIe pre/post_link_speed

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Message-ID: <20250711212952.GA2308100@bhelgaas>
Date: Fri, 11 Jul 2025 16:29:52 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Krishna Chaitanya Chundru <krishna.chundru@....qualcomm.com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
	Jingoo Han <jingoohan1@...il.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Rob Herring <robh@...nel.org>, Jeff Johnson <jjohnson@...nel.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, mhi@...ts.linux.dev,
	linux-wireless@...r.kernel.org, ath11k@...ts.infradead.org,
	qiang.yu@....qualcomm.com, quic_vbadigan@...cinc.com,
	quic_vpernami@...cinc.com, quic_mrana@...cinc.com,
	Jeff Johnson <jeff.johnson@....qualcomm.com>
Subject: Re: [PATCH v4 08/11] PCI: qcom: Add support for PCIe
 pre/post_link_speed_change()

On Mon, Jun 09, 2025 at 04:21:29PM +0530, Krishna Chaitanya Chundru wrote:
> QCOM PCIe controllers need to disable ASPM before initiating link
> re-train. So as part of pre_link_speed_change() disable ASPM and as
> part of post_link_speed_change() enable ASPM back.

Is this a QCOM defect?  Or is there something in the PCIe spec about
needing to disable ASPM during retrain?  What about
pcie_retrain_link()?  Does that work on QCOM?

> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -276,10 +276,16 @@ struct qcom_pcie {
>  	struct dentry *debugfs;
>  	bool suspended;
>  	bool use_pm_opp;
> +	int aspm_state; /* Store ASPM state used in pre & post link speed change */

Whatever this is, it's definitely not an int.  Some kind of unsigned
thing of specified size, at least.