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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-08-08 23:58:38 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-08-12 10:47:55 +0200
commit4eaefe8c621c6195c91044396ed8060c179f7aae (patch)
tree55830586908c8ed32c7e442e41e2aed1b9523651 /drivers/nvme/host/pci.c
parentaccd2dd72c8f087441d725dd916688171519e4e6 (diff)
downloadlinux-4eaefe8c621c6195c91044396ed8060c179f7aae.tar.gz
nvme-pci: Allow PCI bus-level PM to be used if ASPM is disabled
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() so as to instruct the PCI bus type to leave devices handled by the nvme driver in D0 during suspend-to-idle. That was done with the assumption that ASPM would transition the device's PCIe link into a low-power state when the device became inactive. However, if ASPM is disabled for the device, its PCIe link will stay in L0 and in that case commit d916b1be94b6 is likely to cause the energy used by the system while suspended to increase. Namely, if the device in question works in accordance with the PCIe specification, putting it into D3hot causes its PCIe link to go to L1 or L2/L3 Ready, which is lower-power than L0. Since the energy used by the system while suspended depends on the state of its PCIe link (as a general rule, the lower-power the state of the link, the less energy the system will use), putting the device into D3hot during suspend-to-idle should be more energy-efficient that leaving it in D0 with disabled ASPM. For this reason, avoid leaving NVMe devices with disabled ASPM in D0 during suspend-to-idle. Instead, shut them down entirely and let the PCI bus type put them into D3. Fixes: d916b1be94b6 ("nvme-pci: use host managed power state for suspend") Link: https://lore.kernel.org/linux-pm/2763495.NmdaWeg79L@kreacher/T/#t Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Keith Busch <keith.busch@intel.com>
Diffstat (limited to 'drivers/nvme/host/pci.c')
-rw-r--r--drivers/nvme/host/pci.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index db160cee42ad..108e109e99f1 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2846,7 +2846,7 @@ static int nvme_resume(struct device *dev)
struct nvme_dev *ndev = pci_get_drvdata(to_pci_dev(dev));
struct nvme_ctrl *ctrl = &ndev->ctrl;
- if (pm_resume_via_firmware() || !ctrl->npss ||
+ if (ndev->last_ps == U32_MAX ||
nvme_set_power_state(ctrl, ndev->last_ps) != 0)
nvme_reset_ctrl(ctrl);
return 0;
@@ -2859,6 +2859,8 @@ static int nvme_suspend(struct device *dev)
struct nvme_ctrl *ctrl = &ndev->ctrl;
int ret = -EBUSY;
+ ndev->last_ps = U32_MAX;
+
/*
* The platform does not remove power for a kernel managed suspend so
* use host managed nvme power settings for lowest idle power if
@@ -2866,8 +2868,14 @@ static int nvme_suspend(struct device *dev)
* shutdown. But if the firmware is involved after the suspend or the
* device does not support any non-default power states, shut down the
* device fully.
+ *
+ * If ASPM is not enabled for the device, shut down the device and allow
+ * the PCI bus layer to put it into D3 in order to take the PCIe link
+ * down, so as to allow the platform to achieve its minimum low-power
+ * state (which may not be possible if the link is up).
*/
- if (pm_suspend_via_firmware() || !ctrl->npss) {
+ if (pm_suspend_via_firmware() || !ctrl->npss ||
+ !pcie_aspm_enabled(pdev)) {
nvme_dev_disable(ndev, true);
return 0;
}
@@ -2880,7 +2888,6 @@ static int nvme_suspend(struct device *dev)
ctrl->state != NVME_CTRL_ADMIN_ONLY)
goto unfreeze;
- ndev->last_ps = 0;
ret = nvme_get_power_state(ctrl, &ndev->last_ps);
if (ret < 0)
goto unfreeze;