[PATCH 4/4] nvme-pci: Use pci_dev_suspend_retention_supported() API during suspend

[Manivannan Sadhasivam via B4 Relay]

From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>

The pci_dev_suspend_retention_supported() API lets PCI client drivers
know if the platform can retain the device context during suspend. This
is decided based on several factors like:

1. Firmware involvement at the end of suspend
2. Any platform limitation in waking from low power state (L1ss)

And this API might also get extended in the future to cover other platform
specific issues impacting the device low power mode during system suspend.

So use this API instead of checks like pm_suspend_via_firmware(). When this
API returns false, then assume that the platform cannot retain the context
and shutdown the controller. If it returns true, then assume that the
context will be retained and keep the device in low power mode.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxxxxxxxx>
---
 drivers/nvme/host/pci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index b78ba239c8ea..19010330469f 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -3915,6 +3915,7 @@ static int nvme_suspend(struct device *dev)
 	 * use host managed nvme power settings for lowest idle power if
 	 * possible. This should have quicker resume latency than a full device
 	 * shutdown.  But if the firmware is involved after the suspend or the
+	 * platform has any limitation in waking from low power states or the
 	 * device does not support any non-default power states, shut down the
 	 * device fully.
 	 *
@@ -3923,7 +3924,7 @@ static int nvme_suspend(struct device *dev)
 	 * 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 (!pci_dev_suspend_retention_supported(pdev) || !ctrl->npss ||
 	    !pcie_aspm_enabled(pdev) ||
 	    (ndev->ctrl.quirks & NVME_QUIRK_SIMPLE_SUSPEND))
 		return nvme_disable_prepare_reset(ndev, true);

-- 
2.51.0