Re: [PATCH 1/2] PCI/PM: refactor pci_pm_suspend_noirq()

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On 2/24/2022 9:29 PM, Rajvi Jingar wrote:
The state of the device is saved during pci_pm_suspend_noirq(), if it has
not already been saved, regardless of the skip_bus_pm flag value. So
skip_bus_pm check is removed before saving the device state.

Signed-off-by: Rajvi Jingar <rajvi.jingar@xxxxxxxxx>
Suggested-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
---
  drivers/pci/pci-driver.c | 15 ++-------------
  1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 588588cfda48..ac3f7e1676a9 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -834,20 +834,9 @@ static int pci_pm_suspend_noirq(struct device *dev)
  		}
  	}
- if (pci_dev->skip_bus_pm) {
-		/*
-		 * Either the device is a bridge with a child in D0 below it, or
-		 * the function is running for the second time in a row without
-		 * going through full resume, which is possible only during
-		 * suspend-to-idle in a spurious wakeup case.  The device should
-		 * be in D0 at this point, but if it is a bridge, it may be
-		 * necessary to save its state.
-		 */

The comment is outdated, but the role of skip_bus_pm needs to be explained.  It only applies to the bridge with a child in D0 case now, because the other one has gone away, so I would put a new comment before the reworked check below.


-		if (!pci_dev->state_saved)
-			pci_save_state(pci_dev);
-	} else if (!pci_dev->state_saved) {
+	if (!pci_dev->state_saved) {
  		pci_save_state(pci_dev);
-		if (pci_power_manageable(pci_dev))

For example:

/*

 * If the device is a bridge with a child in D0 below it, it needs to stay in D0, so check

 * skip_bus_pm to avoid putting it into a low-power state in that case.

 */


+		if (!pci_dev->skip_bus_pm && pci_power_manageable(pci_dev))
  			pci_prepare_to_sleep(pci_dev);
  	}





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