[PATCH v3] HID: intel-ish-hid: Replace PCI_DEV_FLAGS_NO_D3 with pci_save_state

[Kai-Heng Feng]

PCI_DEV_FLAGS_NO_D3 should not be used outside of PCI core.

Instead, we can use pci_save_state() to hint PCI core that the device
should stay at D0 during suspend. By doing so, PCI core will let the
upstream bridges also stays at D0 so the entire hierarchy is in the
correct power state as PCI spec mandates.

Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
---
v3:
 - Use multi-line comments.
v2:
 - Wording change.

 drivers/hid/intel-ish-hid/ipc/pci-ish.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/intel-ish-hid/ipc/pci-ish.c b/drivers/hid/intel-ish-hid/ipc/pci-ish.c
index f491d8b4e24c..c6d48a8648b7 100644
--- a/drivers/hid/intel-ish-hid/ipc/pci-ish.c
+++ b/drivers/hid/intel-ish-hid/ipc/pci-ish.c
@@ -106,6 +106,11 @@ static inline bool ish_should_enter_d0i3(struct pci_dev *pdev)
 	return !pm_suspend_via_firmware() || pdev->device == CHV_DEVICE_ID;
 }
 
+static inline bool ish_should_leave_d0i3(struct pci_dev *pdev)
+{
+	return !pm_resume_via_firmware() || pdev->device == CHV_DEVICE_ID;
+}
+
 /**
  * ish_probe() - PCI driver probe callback
  * @pdev:	pci device
@@ -215,9 +220,7 @@ static void __maybe_unused ish_resume_handler(struct work_struct *work)
 	struct ishtp_device *dev = pci_get_drvdata(pdev);
 	int ret;
 
-	/* Check the NO_D3 flag to distinguish the resume paths */
-	if (pdev->dev_flags & PCI_DEV_FLAGS_NO_D3) {
-		pdev->dev_flags &= ~PCI_DEV_FLAGS_NO_D3;
+	if (ish_should_leave_d0i3(pdev) && !dev->suspend_flag) {
 		disable_irq_wake(pdev->irq);
 
 		ishtp_send_resume(dev);
@@ -281,8 +284,11 @@ static int __maybe_unused ish_suspend(struct device *device)
 			 */
 			ish_disable_dma(dev);
 		} else {
-			/* Set the NO_D3 flag, the ISH would enter D0i3 */
-			pdev->dev_flags |= PCI_DEV_FLAGS_NO_D3;
+			/*
+			 * Save state so PCI core will keep the device at D0,
+			 * the ISH would enter D0i3
+			 */
+			pci_save_state(pdev);
 
 			enable_irq_wake(pdev->irq);
 		}
-- 
2.17.1