[+cc other folks interested in PTM from https://lore.kernel.org/r/20220408153159.106741-1-kai.heng.feng@xxxxxxxxxxxxx] On Thu, Apr 14, 2022 at 07:54:02PM +0200, Rafael J. Wysocki wrote: > On 3/25/2022 8:50 PM, Rajvi Jingar wrote: > > For the PCIe devices (like nvme) that do not go into D3 state still need to > > disable PTM on PCIe root ports to allow the port to enter a lower-power PM > > state and the SoC to reach a lower-power idle state as a whole. Move the > > pci_disable_ptm() out of pci_prepare_to_sleep() as this code path is not > > followed for devices that do not go into D3. This patch fixes the issue > > seen on Dell XPS 9300 with Ice Lake CPU and Dell Precision 5530 with Coffee > > Lake CPU platforms to get improved residency in low power idle states. > > > > Fixes: a697f072f5da ("PCI: Disable PTM during suspend to save power") > > Signed-off-by: Rajvi Jingar <rajvi.jingar@xxxxxxxxx> > > Suggested-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx> > > --- > > v1 -> v2: add Fixes tag in commit message > > v2 -> v3: move changelog after "---" marker > > v3 -> v4: add "---" marker after changelog > > --- > > drivers/pci/pci-driver.c | 10 ++++++++++ > > drivers/pci/pci.c | 10 ---------- > > 2 files changed, 10 insertions(+), 10 deletions(-) > > > > diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c > > index 8b55a90126a2..ab733374a260 100644 > > --- a/drivers/pci/pci-driver.c > > +++ b/drivers/pci/pci-driver.c > > @@ -847,6 +847,16 @@ static int pci_pm_suspend_noirq(struct device *dev) > > if (!pci_dev->state_saved) { > > pci_save_state(pci_dev); > > + /* > > + * There are systems (for example, Intel mobile chips since Coffee > > + * Lake) where the power drawn while suspended can be significantly > > + * reduced by disabling PTM on PCIe root ports as this allows the > > + * port to enter a lower-power PM state and the SoC to reach a > > + * lower-power idle state as a whole. > > + */ > > + if (pci_pcie_type(pci_dev) == PCI_EXP_TYPE_ROOT_PORT) > > + pci_disable_ptm(pci_dev); Why is disabling PTM dependent on pci_dev->state_saved? The point of this is to change the behavior of the device, and it seems like we want to do that regardless of whether the driver has used pci_save_state(). Bjorn
