[PATCH 1/1][SRU][OEM-B] UBUNTU: SAUCE: PCI/PM: Don't call pci_finish_runtime_suspend()

[AceLan Kao]

BugLink: https://bugs.launchpad.net/bugs/1842388

Don't call pci_finish_runtime_suspend() if runtime PM callback functions
are not provided. It leads to backport-iwlwifi driver fails to wakes up
from runtime suspend.

This commit could be reverted after backport-iwlwifi-dkms 7906 driver is
released in Ubuntu archive.

Signed-off-by: AceLan Kao <acelan.kao at canonical.com>
---
 drivers/pci/pci-driver.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 34327a5ddf4c..e0809aff63bf 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -1323,6 +1323,10 @@ static int pci_pm_runtime_suspend(struct device *dev)
 
 	if (!pci_dev->state_saved) {
 		pci_save_state(pci_dev);
+
+		if (!pm || !pm->runtime_suspend)
+			return -ENOSYS;
+
 		pci_finish_runtime_suspend(pci_dev);
 	}
 
-- 
2.17.1