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

[Bjorn Helgaas <helgaas@kernel.org>]

On Sun, Jan 26, 2025 at 10:33:09AM +0530, Manivannan Sadhasivam wrote:
> On these platforms, power to the PCIe bus is not retained if the SoC enters
> its own deep low power state called, CX power collapse state during system
> suspend. Once the SoC resumes after going through CX power collapse, all
> the PCIe bus state will be lost. So the NVMe devices on these platforms
> won't resume properly, rendering the machines useless until forcefully
> restarted by the users.

I guess "forcefully restarted" means a power cycle?

> +++ b/drivers/nvme/host/pci.c
> @@ -3162,6 +3162,16 @@ static unsigned long check_vendor_combination_bug(struct pci_dev *pdev)
>  	if (dmi_match(DMI_BOARD_NAME, "LXKT-ZXEG-N6"))
>  		return NVME_QUIRK_NO_APST;
>  
> +	/*
> +	 * 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.