Re: [PATCH] nvme-pci: Fix system hang when ASPM L1 is enabled during suspend

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, May 02, 2025 at 11:20:51AM +0800, hans.zhang@cixtech.com wrote:
> From: Hans Zhang <hans.zhang@cixtech.com>
> 
> When PCIe ASPM L1 is enabled (CONFIG_PCIEASPM_POWERSAVE=y), certain

CONFIG_PCIEASPM_POWERSAVE=y only sets the default.  L1 can be enabled
dynamically regardless of the config.

> NVMe controllers fail to release LPI MSI-X interrupts during system
> suspend, leading to a system hang. This occurs because the driver's
> existing power management path does not fully disable the device
> when ASPM is active.

I have no idea what this has to do with ASPM L1.  I do see that
nvme_suspend() tests pcie_aspm_enabled(pdev) (which seems kind of
janky and racy).  But this doesn't explain anything about what would
cause a system hang.

> The fix adds an explicit device disable and reset preparation step
> in the suspend path after successfully setting the power state.
> This ensures proper cleanup of interrupt resources even when ASPM
> L1 is enabled, preventing the system from hanging during suspend.

Maybe there's a clue in the 600 lines of debug output that I trimmed,
but without some interpretation, I have no idea how to find it.

Unless you see similar problems on other systems, I would suspect an
issue with the SoC or the SoC driver where you do see problems.

Bjorn