bus: mhi: pci_generic: Use generic PCI power management

The PCI core can take care of proper PCI suspend/resume operations, but
this is discarded when the driver saves PCI state by its own. This
currently prevents the PCI core to enable PME (for modem initiated
D3 exit) which is requested for proper runtime pm support.

This change deletes explicit PCI state-saving and state-set from
suspend callback, letting the PCI doing the appropriate work.
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614971808-22156-5-git-send-email-loic.poulain@linaro.orgSigned-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

drivers/bus/mhi/pci_generic.c

@@ -545,9 +545,12 @@ static int mhi_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 
 	pci_set_drvdata(pdev, mhi_pdev);
 
-	/* Have stored pci confspace at hand for restore in sudden PCI error */
+	/* Have stored pci confspace at hand for restore in sudden PCI error.
+	 * cache the state locally and discard the PCI core one.
+	 */
 	pci_save_state(pdev);
 	mhi_pdev->pci_state = pci_store_saved_state(pdev);
+	pci_load_saved_state(pdev, NULL);
 
 	pci_enable_pcie_error_reporting(pdev);
 
@@ -718,10 +721,8 @@ static int  __maybe_unused mhi_pci_suspend(struct device *dev)
 	/* Transition to M3 state */
 	mhi_pm_suspend(mhi_cntrl);
 
-	pci_save_state(pdev);
 	pci_disable_device(pdev);
 	pci_wake_from_d3(pdev, true);
-	pci_set_power_state(pdev, PCI_D3hot);
 
 	return 0;
 }
@@ -733,14 +734,13 @@ static int __maybe_unused mhi_pci_resume(struct device *dev)
 	struct mhi_controller *mhi_cntrl = &mhi_pdev->mhi_cntrl;
 	int err;
 
-	pci_set_power_state(pdev, PCI_D0);
-	pci_restore_state(pdev);
-	pci_set_master(pdev);
-
 	err = pci_enable_device(pdev);
 	if (err)
 		goto err_recovery;
 
+	pci_set_master(pdev);
+	pci_wake_from_d3(pdev, false);
+
 	/* Exit M3, transition to M0 state */
 	err = mhi_pm_resume(mhi_cntrl);
 	if (err) {