linux-kernel - Re: [PATCH] nvme-pci: Use NVME_QUIRK_SIMPLE_SUSPEND for Qualcomm Snapdragon 8cx Gen 3 platforms

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Message-ID: <20250210063605.yp5rkraain5oqxka@thinkpad>
Date: Mon, 10 Feb 2025 12:06:05 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Christoph Hellwig <hch@....de>
Cc: Bjorn Helgaas <helgaas@...nel.org>, kbusch@...nel.org, axboe@...nel.dk,
	sagi@...mberg.me, linux-nvme@...ts.infradead.org,
	linux-kernel@...r.kernel.org, andersson@...nel.org,
	konradybcio@...nel.org, rafael@...nel.org, ulf.hansson@...aro.org
Subject: Re: [PATCH] nvme-pci: Use NVME_QUIRK_SIMPLE_SUSPEND for Qualcomm
 Snapdragon 8cx Gen 3 platforms

On Mon, Feb 10, 2025 at 05:04:46AM +0100, Christoph Hellwig wrote:
> On Sat, Feb 08, 2025 at 12:51:24PM -0600, Bjorn Helgaas wrote:
> > > +	/*
> > > +	 * Qualcomm Snapdragon 8cx Gen 3 (SC8280XP) platforms doesn't retain
> > > +	 * power to the PCIe bus after entering low power CX power collapse
> > > +	 * state during system suspend. So shutdown the NVMe devices to have a
> > > +	 * working system suspend on these platforms.
> > > +	 */
> > > +	if (dmi_match(DMI_PRODUCT_FAMILY, "SCP_MAKENA") ||
> > > +	    dmi_match(DMI_PRODUCT_FAMILY, "ThinkPad X13s Gen 1"))
> > > +		return NVME_QUIRK_SIMPLE_SUSPEND;
> > 
> > I certainly acknowledge that this is a big problem for users.  At the
> > same time, this seems like a maintenance nightmare of
> > platform-specific hacks scattered through endpoint drivers.
> 
> Yes.  And it's what we stated that we won't do multiple times.

Multiple times? As I stated in the commit message, this quirk is *not* going to
be extended for any Qcom platforms as the rest of them can retain the PCIe power
state during CX Power Collapse.

And we don't need this quirk in any other endpoint drivers as this chipset is
mostly used in Laptop form factors and only the NVMe driver is found to be
causing the issues. Rest of the endpoint drivers (WLAN, Modem) are all coping
with PCIe power going down during system suspend.

> This needs to be taken on in the firmware or at least core PCI/PM
> code.

That would be the end goal. Once that happens, we can revert this patch.
Unfortunately, we need an interim solution to satisfy users.

- Mani

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