From mboxrd@z Thu Jan 1 00:00:00 1970 From: rjw@rjwysocki.net (Rafael J. Wysocki) Date: Wed, 07 Aug 2019 12:14:08 +0200 Subject: [PATCH] nvme-pci: Do not prevent PCI bus-level PM from being used In-Reply-To: <1893355.EP2830DdO9@kreacher> References: <4323ed84dd07474eab65699b4d007aaf@AUSX13MPC105.AMER.DELL.COM> <20190731221956.GB15795@localhost.localdomain> <1893355.EP2830DdO9@kreacher> Message-ID: <2081634.8PS0KMhuBW@kreacher> On Wednesday, August 7, 2019 11:53:44 AM CEST Rafael J. Wysocki wrote: > From: Rafael J. Wysocki > > One of the modifications made by commit d916b1be94b6 ("nvme-pci: use > host managed power state for suspend") was adding a pci_save_state() > call to nvme_suspend() in order to prevent the PCI bus-level PM from > being applied to the suspended NVMe devices, but if ASPM is not > enabled for the target NVMe device, that causes its PCIe link to stay > up and the platform may not be able to get into its optimum low-power > state because of that. > > For example, if ASPM is disabled for the NVMe drive (PC401 NVMe SK > hynix 256GB) in my Dell XPS13 9380, leaving it in D0 during > suspend-to-idle prevents the SoC from reaching package idle states > deeper than PC3, which is way insufficient for system suspend. > > To address this shortcoming, make nvme_suspend() check if ASPM is > enabled for the target device and fall back to full device shutdown > and PCI bus-level PM if that is not the case. > > Fixes: d916b1be94b6 ("nvme-pci: use host managed power state for suspend") > Link: https://lore.kernel.org/linux-pm/2763495.NmdaWeg79L at kreacher/T/#t > Signed-off-by: Rafael J. Wysocki > --- I should have used a better subject for this patch. I'll resend it with a changed subject later, but for now I would like to collect opinions about it (if any). Cheers!