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From: Heiner Kallweit <hkallweit1@gmail.com>
To: Bjorn Helgaas <bhelgaas@google.com>
Cc: "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Potential issue with pci_prepare_to_sleep if there's no platform support for D3cold transition
Date: Mon, 21 Apr 2025 22:05:59 +0200	[thread overview]
Message-ID: <62de9027-e4cd-4192-90e8-64f4c4a8fe4b@gmail.com> (raw)

If there's no platform support for transition to D3cold, then
pci_set_power_state(dev, D3cold) still returns 0, even though
power state is transitioned to D3hot only. We called
pci_enable_wake(dev, D3cold, wakeup) before, therefore PME for
D3hot may not be enabled. Is this a bug?

Background:
In __pci_set_power_state we have the following:

error = pci_set_low_power_state(dev, PCI_D3hot, locked);
if (pci_platform_power_transition(dev, PCI_D3cold))
	return error;

The acpi_pci_set_power_state() stub returns -ENODEV.
Therefore, if error=0,  __pci_set_power_state() will
return 0 if pci_platform_power_transition() fails.


             reply	other threads:[~2025-04-21 20:04 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-21 20:05 Heiner Kallweit [this message]
2025-04-22  6:27 ` Potential issue with pci_prepare_to_sleep if there's no platform support for D3cold transition Lukas Wunner
2025-04-22 11:43   ` Rafael J. Wysocki
2025-04-23  9:32     ` Heiner Kallweit
2025-04-23  9:45       ` Heiner Kallweit

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